1. There can be no doubt that Ankylostomiasis has obtained a very firm hold in the coastal districts of North Queensland, and every effort should be made to arrest its spread, and if possible eradicate it.

2. Experience in other parts of the world, notably the United States and Germany, has demonstrated the great difficulty of coping with the disease, even with the most energetic of preventive measures.

3. The disease gives rise to much sickness and inefficiency especially amongst children, and although competent medical treatment is usually efficacious the most satisfactory and permanent results are to be expected in the direction of prevention.

4. The chief preventive measures are individual cleanliness and thorough and rapid destruction of night soil and deposits of faecal material.

5. In the presence of a properly organised sanitary system, intelligently utilised, there should be little or no risk of infection. It is the promiscuous distribution of excreta that is the chief source of the spread of infection.

6. If the indiscriminate deposit of faecal material be not prevented, the matter resolves itself into a problem of considerable difficulty.

7. The more commonly used disinfectants, if thoroughly employed, would render the faecal material comparatively innocuous, but their use is not less laborious than the proper removal of the faecal material and its disposal in properly constructed receptacles.

8. Common table salt has a decidedly injurious effect upon the hook-worm eggs but it requires to be brought into very intimate contact with the infected material. The process of merely sprinkling the surface is almost futile unless the salt be used in enormous quantities.

9. When mixed with faecal matter, sand promotes the development of hook-worm larvae, but when used as a covering of a certain depth it arrests development.

10. Exposure to direct sunlight of sufficient intensity kills hook worm eggs and larvae very rapidly.

This interesting and peculiar parasite was apparently first noted and studied by George Newport in 1831. That writer, however, was unable to publish his observations till 1849, by which date he had been anticipated in authorship by Francis Walker for the specific name, and by J. O. Westwood for the generic. With the latter Newport engaged in a somewhat protracted controversy touching priority of name, morphology, habits, etc., of Melittobia. There can be no doubt that Westwood's genus, very briefly characterised in Proc. Ent. Soc. Lond. for 5th July, 1847, p. xviii, must stand. The part of the proceedings containing this page was published on 12th January, 1848. As the purpose of the present notes is chiefly to offer a more accurate description of M. acasta, and as, besides, I am at present engaged in revising the whole genus, it does not seem necessary to say much on the habits of the insect. M. acasta is markedly polyphagous; never apparently a true hyperparasite, it attacks everything within its limited range of action. Already it has been bred from a long list of hosts, and somewhat contradictory conclusions about the insect's parasitic status and economic value may be drawn from its host attachment. Thus it may be a pest in nests of bees, wasps, etc.; a species of Melittobia again proved a serious menace in the laboratory to Tachinids introduced into the U.S.A. to combat the Gipsy Moth, but possibly, the insect plays, or may be induced to play, a useful part in destroying dipterous puparia in or near houses, or in surroundings where the adult may skulk secure. For Melittobia dislikes light, and the ♀ flies little, though when once established in a suitable environment, it is hard to dislodge.

♂ ♀. Head (Fig. 2, A and B) long with well-marked postero-lateral angles, and distinctly angled posteriorly; bare above, behind the pre-antennal suture, except for two postero-lateral spines (1, 1). Antennae similar, the first joint of the ♂ larger and broader. Tergites and sternites indistinctly developed, consisting of small discontinuous chitinous areas at the base of the bristle; pleurties reduced, projecting shortly above and below in minutely denticulate or frayed points.

In a recent number of Parastilogy (1916) an account was given of the species of Triodontophorus and Oesophagodontus found in the alimentary tract of horses in the neighbourhood of Birmingham, more particularly in the Redditch district of Worcestershire. In company with the worms of these two genera were several species of Cylichnostomum, occurring in some of the hosts in considerable numbers both in the colon and caecum.

When eggs of Ascaris lumbricoides Lin. or A. suilla Duj. containing mature embryos gain entrance to the alimentary canal of the sewer rat, Mus decumanus, or the mouse, M. musculus, they hatch. It is not possible to say at present in what part of the alimentary canal hatching takes place. (The number of animals suitable for experiment at the disposal of the writer is unfortunately so small that he is unable to devote any of them to the working out of the details of the process.) A certain proportion of the larvae thus liberated escape in the faeces where under suitable circumstances they can live for at least three days. It is, however, probable they ultimately succumb and that this is not a true road of development.

The majority of the larvae gain entrance into the body of the host. The exact point of entrance and the time after hatching at which entrance takes place have not been determined. Some animals show signs of illness on the second day after infection. The time elapsing between infection and the entrance of the larvae into the body is therefore probably not more than two days.

Larvae are found in the lungs and liver of the host not later than four days after infection and possibly as early as two days. Sections of the tissues show that they are situated in the air vesicles of the lung and in the blood capillaries of the liver close to the interlobular branches of the portal vein.

Larvae are not found in the liver after the fifth day from infection. They are found in the bronchi about the seventh day and in the trachea on the eighth day.

No larvae are found in any portion of the lung on the ninth day after infection. Dead larvae have been found in the stomach and rectum on the ninth day after the last infection.

The route by which the larvae reach these sites is of course not definitely proved but from anatomical considerations it is hardly possible that it can be other than one of the two following (the diameter of the larva is three times that of a red blood corpuscle of the mouse. The larva could therefore not pass through the lumen of an ordinary capillary vessel):

(1) Boring through the wall of the stomach or intestine the larva enters a mesenteric venule and is carried to the liver. It is here arrested at the entrance to the hepatic capillary plexus and it is for this reason that so many larvae are found in the capillaries close to the interlobular veins. The liver undergoes extreme and acute fatty degeneration so that the larvae are able to penetrate along the capillaries between the degenerated columns of liver cells to the hepatic venules. Thence they pass in the hepatic vein to the heart and by the pulmonary artery to the lung. They are of course at once arrested by the pulmonary capillary field. Embolism of the smaller branches of the pulmonary artery takes place with haemorrhage around these arterioles. The larvae readily work their way along with the effused blood into the air vesicles and thence into the bronchi and trachea.

(2) The larva after hatching in the stomach or duodenum travels up the bile duct and reaches the bile capillaries of the interlobular zone. It here bores its way through the degenerated liver tissues and reaching a hepatic venule continues its course as in the first case.

During the residence in the body of the rat or mouse the larvae grow from a length of 0·22 mm. to 1·4 mm. The proportion length of oesophagus/total length diminishes from 1/2·5 to 1/6·1. The ventral line which is the greatest of the longitudinal lines in the embryo is reduced to the same dimensions as the dorsal and lateral lines. The ventral gland (the rudiment of the excretory system) is developed from a cell of the ventral line, enlarges very greatly, acquires the massive nucleus characteristic of Ascaris larvae (Stewart, 1906; Baylis, 1916) and finally develops its duct from the cells of the ventral line. The intestine, anal canal and anus become pervious. The rudiment of the female gonads appears.

General comparative note on the two species.

Pediculus humanus (vestimenti) is a larger, more robust and less active insect than P. capitis,—the ♀♀ having a relatively greater egg-carrying capacity than those of the head louse. The eggs are larger and the number laid (under the conditions of these experiments) is greater, while the habits associated with egg laying differ, although placing the ♀♀ of humanus under conditions applicable to capitis or vice versa may induce a considerable degree of uniformity. Cross pairings between the insects are easily brought about and the offspring are fertile inter se. Hybrid strains were maintained until the F. 3 generation and there seemed no reason, judging from breeding results, why such strains should not be continued indefinitely. Nevertheless the marked disparity in the sexes of the F. 1 generation of some of the crosses between P. capitis ♂ and P. humanus ♀ suggests that the parents are specifically distinct.

No such obvious disparity occurred between the sexes of the F. 2 and F. 3 hybrid generation, or of either of the pure stocks.

Habits. The body louse exhibits some of the habits of a gregarious animal especially during the moulting phases, also a preference for returning to the same spot for oviposition, which leads to the clustering of its eggs. These habits are shown, though in a less marked degree, by P. capitis, and it is possible therefore that they are to some extent the outcome of confinement. Pairing within both species took place at any time during day or night, and was very frequently observed after feeding. ♂♂ with but little food in their alimentary tract were, however, often seen in coitus. The period during which the insects remained paired was frequently observed to be over an hour, but no upper limit was defined.

A ♂ of P. humanus fertilized 18 out of 21 ♀♀ placed with him in succession. Four attempts with P. capitis were less successful; one ♂ fertilized ten ♀♀ and very possibly might have equalled the P. humanus record but for a scarcity of virgin ♀♀ while the experiment was in progress. The longest period during which a ♀ of P. humanus retained the power to lay fertile eggs in the absence of a ♂ was 20 days, usually it would seem to be from 16 to 18 days. In the case of P. capitis the period was shorter; 12 days being the longest ascertained period, while it was more usually from seven to eleven days.

The greatest number of eggs laid by any one ♀ of P. humanus was 295, an average of 6·4 per day—the daily average of a number of ♀♀ being 5·1. P. capitis ♀♀ showed a lower fecundity, the highest record being 141 with a daily average of 4—the general average being 3·7. These figures are probably exceeded under natural conditions. An experiment in differential feeding with P. humanus (Table VIII) shows clearly that fecundity is dependent on feeding. When extra feeding time over and above seven hours per day was given the average for four ♀♀ was eight per day. It is reasonable to suppose that the average for P. capitis would also be increased by unrestricted feeding.

The fertility of the eggs laid was not affected by increased feeding. The greatest number of fertilized eggs laid by a ♀ P. humanus after the removal of the ♂ was 115 (♀ No. 9), with a ♀ showing a higher daily laying average this might well be exceeded. With P. capitis the parallel figure is 70 (♀ No. 9). The ♀♀ of both species, after arriving at maturity, started oviposition irrespective of their having paired or not, but eggs laid by virgin ♀♀ were invariably infertile.

Length of life. The life of the ♂ P. humanus used in the experiment recorded in Table I was 32 days; the longest ♀ life was 46 days, with an average of 34. For P. capitis the figures were: ♂ life 30 days; ♀ life 38 days, with an average of 27 days. Whether or not the average lives of the insects would be extended by unrestricted feeding is an open question.

The life of the hybrid insects was not noticeably shorter than that usual for P. humanus, and they seemed to thrive better than P. capitis.

Tests made with unfed P. humanus showed that the longest lives were at a medium temperature of 16° to 18° C., many of the insects living from three to four days, while two lived five and one lived seven days. At 24·5° C. all died within five days. At 36·1° C. all died within three days.

Newly-hatched larvae, unless fed, lived less than 24 hours at 36·1° C., and when kept in a box in the vest pocket they lived but little more than a day; none survived a second day.

Adults kept in a box in the side pocket of a coat lived five days without food; this was in March.

Moulting. 40 young lice were reared in a box carried in a vest pocket and particulars of their moulting recorded.

1st moult: 3% moulted on the 3rd day; 42% on the 4th and 55% on the 5th day.

2nd moult: 15% moulted on the 7th day; 72% on the 8th and 13% on the 9th day.

3rd moult: 5% moulted on the JOth day; 3% on the 11th, 55% on the 12th, 32% on the 13th day, while 5% took 14 days to reach maturity.

The ♂♂ usually mature rather earlier than the ♀♀

Cold. Active specimens of P. humanus survived two days at a temperature of −2·3° C. to −1·1° C., but none recovered after exposure to these conditions for a week.

Hatching of eggs. Table IX shows that under humid conditions at 31° C. 3% of the 1300 eggs tested hatched on the 7th day; 56% on the 8th; 33% on the 9th; 8% on the 10th and ·2% later on the same day or on the 11th.

A test of batches of eggs taken from a stock box, some of which must have been laid several days previously, showed that none hatched at 15·6°−18·4° C., while at 24·5° C. there was considerable egg mortality, and the hatching period was spread over a longer period than usual, though not to the extent mentioned by Warburtou (1909); at 36·l° C. hatching was spread over five days and the mortality was not excessive.

To give some idea of the possible rate of multiplication of P. humanus we may estimate the egg period as 12 days and a further 12 days to the maturity of the ♀♀. Allowing an average of eight eggs per day, spread over a fertility period of 40 days, we find that, during her life, a single ♀ may have 4160 offspring.

During the two years preceding the outbreak of war, Dr Hindle was engaged in researches on the biology of lice. Soon after the war began he joined the army, leaving his notes with me. He has now been in France for over a year and is serving as Captain in the Royal Engineers. An abstract of his work has been set up in type for many months for publication by the Local Government Board but his contribution has been withheld unavoidably through a desire that it should be supplemented by further work which has since been conducted in the Quick Laboratory.

At the time investigators were trying to cultivate the amoebae of the human intestine (Entamoeba coli and E. histolytica), amoebae were often encountered in the cultures which were referred to the species “Amoeba limax,” with many sub-species. Subsequently it was found that the cysts of these cultural amoebae are very common and that it is possible to cultivate amoebae from nearly every source. Consequently it was concluded that these forms do not really live in the human intestine but that the cultural amoebae developed from cysts, occasionally ingested with food, the cysts not having developed in the intestine. This is Walker's (1911) view, but Chatton and Lalung Bonaire (1912) hold that the limax amoebae (hereafter called limax) can live in the intestine, not only in the form of cysts but also as motile amoebae. Cultures made from these stools showed amoebae and uninucleate cysts. The latter were not found in the faeces, which showed only the motile stages, without however any signs of division. The cultures showed this amoeba to be of the common Umax-type with a vesicular nucleus containing a large karyosome. These observations are important because they contradict the hypothesis that Entamoebae when cultivated show the features of limax.

(1) In the discharge from a case of acute urethritis spirochaetes were found which it is believed were the causal agent of the disease.

(2) The spirochaetes were most commonly 8μ to 12μ in length, and showed four or five spirals; but the range in the three hundred parasites measured was from 5μ, to 20μ. They appeared to multiply both by longitudinal and transverse division and by the formation of coocoid bodies. The parasites passed through an intracellular phase which seemed to be as follows: some of the spirochaetes enter the epithelial scales lining the urethra, become quiescent, and break up into coccoid bodies. These bodies multiply so as to form masses of granules from which young spirochaetes develop, grow to about the normal size, and eventually escape.

(3) The name Spirochaeta urethraeis proposed for the parasite.

Owing to the active interest now being taken in all that concerns lice and their habits, especially in connection with the war, it seems expedient to forestall a fuller publication, now in preparation, by giving an account of the copulatory apparatus and the curious process of copulation in Pediculus humanus Linn.