In the blood of the above mammals there was found in varying proportions those enigmatical bodies recently described by Theiler as Protozoa under the name Anaplasma marginale, but more generally known as “marginal points” or “coccus-like bodiees.”

The parasite which I have here described has a life-history containing two distinct stages: a vegetative stage and a sporogonic stage. During the vegetative period multinucleate individuals divide by irregular schizogony producing young uni- or paucinucleate individuals. During the sporogonic period, a number of trophozoites unite to form an aggregation which becomes encysted. In the encysted individuals (the pansporoblasts) there is an increase of nuclear substance and a reduction of plasmatic substance. The nuclei become arranged in pairs and by successive unequal divisions the pansporoblasts produce thesporoblasts which contain a pair of nuclei each. During the formation of the sporoblasts there is an increase of protoplasmatic substance. The sporoblasts become spores by the thickening of their pelliculae.

At first the spores contain two nuclei, finally they become mononucleate. This must be explained by the fusion of the two nuclei.

This nuclear fusion is probably to be interpreted as a paedogamous autogamy (in accordance with the nomenclature of Hartmann, 1909).

The methods so successfully used in ridding Panama of yellow fever and delimiting malarial fever have been equally valuable in checking an epidemic of Equine Trypanosorniasis in the Canal Zone.

In a paper published last year, I described the female, nymph and larva of Ixodes caledonicus. Having regard to the views expressed in my recent paper on the adaptation of ticks to the habits of their hosts, I wrote to Mr William Evans, in Edinburgh, asking him, if possible, to kindly search the dove-cot at Dunipace, Stirlingshire, for the missing male which he would probably find in the habitat of the host, the domestic pigeon. On 25 May, 1911, Mr Evans discovered two ticks, a male and female in copula, in the dove-cot, and he sent the specimens to me for identification. The female accords with my published description of caledonicus. The male is here described for the first time, and it is interesting to find that it agrees in structure and habits with what was to be expected according to the theory advanced by me in the second paper I have referred to.

My attention was first directed to this Cestode in 1906 when I was asked to examine several specimens of edible fish which had been exposed for sale in the public markets and had been condemned as human food on account of the presence of obvious, intrusive bodies in the flesh. In three of these cases the muscles of the flesh of the fishes—a Halibut, a Megrim and a Hake—contained cysts which enclosed the larvae of a Tetrarhynchid, and on examination the latter was identified as T. erinaceus from the peculiar nature of the armature of the proboscides. In another case the wall of the stomach of a Halibut was also infected with the same larvae. Acting on an obsolete principle of Border Law the Fish Inspectors promptly condemned the fishes and then caused them to be examined. I do not think there was any valid reason for the condemnation of the articles of food, for I can find no reference in the literature to the presence of Tetrarhynchids in the human alimentary canal, and there does not appear to be any question of a possible communication of a parasite by the consumption, as food, of such infected flesh. Further the number of larvae present was far too few to lead to any emaciation of the fish, or to the likelihood of the production of toxic substances in the flesh of the animal. Nevertheless the Inspectors probably acted in the interests of the public health in condemning such articles of food as contained obvious cyst-like structures in the flesh, as to the precise nature of which they were ignorant, since there is always the possibility that these bodies might be detrimental to the health of those eating them.

A comparison of the descriptions of the morphological characteristics of Filaria loa by previous authors shows differences which are explained by the study of our uninjured specimens. We have prepared a table (q.v.) which shows the results of the work of various observers together with our own. We believe that most of the drawings so far published are somewhat misleading; we have, therefore, drawn the essential parts as seen through the microscope with an entire diameter and a portion of a longitudinal section in focus. The drawings are not composite or schematic but have been made on a large scale with accuracy in the measurements so as to represent the different parts in proper proportion (see Plate).

In the following pages an attempt has been made to give a short summary of our knowledge of the Relapsing Fever of Tropical Africa, and also to include the results of my own experiments and observations on this disease. The literature on the subject is already somewhat considerable and widely scattered, therefore no apology is needed for bringing it together.

The grass in the vicinity of the town of Lourenço Marques is often infested by larval ticks, especially in places frequented by cattle. These ticks are so numerous as to constitute a veritable scourge, since they attack a variety of animals, and man is frequently a victim to their onslaughts. The ticks are especially prevalent in July and August. Their bites may produce merely a local effect, but in some persons general symptoms may follow.

Dysentery is usually classified as (i) bacillary, and (ii) amoebic.

In 1898 Shiga described a bacillus (B. dysenteriae, also known as Shiga's bacillus), as the cause of epidemic dysentery in Japan. Since then his observations have been, in the main, confirmed. Other varieties of dysentery bacilli have been described and “Bacillary Dysentery” seems now to be a well-defined disease capable of study by ordinary bacteriological methods.

The study of the life-histories of digenetic Trematodes is as yet in its infancy. Many new adult forms are described every year, but very little is known of the life-history of any of these. It is even impossible in the majority of cases to say what sort of larval form is characteristic of any group. Having worked for some years at the study of Trematode larvae I thought it would be of some use to bring together all the work so far done on British marine cercariae in order to form a nucleus round which future work may be centred.

This method is especially applicable to the blood and body fluids of Invertebrates in which true clotting does not occur, and in which the proportion of proteid substances in the serum is not high.

The interesting Note by Dr Sant' Anna, which precedes this paper, leads me to record some observations of a somewhat similar nature to those he has reported. My information is derived from three letters received from Africa, and from Dr Hindle.

The following is a brief description of a blood worm which was first observed by Mr J. W. Kehoe, one of the technical assistants at the Federal Laboratory. The parasite has been found in squirrels coming from almost all parts of California east of the Sierra Nevada Mountains, and between the Mexican border and the Sacramento River (between 33° and 38° North Latitude).

In this brief note it is not my intention to enter into detailed criticism, but merely to express my surprise and that of other proto-zoologists, that the personal opinions of the Recorder should be allowed insertion in the Zoological Record (1909) which is also the International Catalogue of Zoological Scientific Literature. Against this procedure I beg to record an emphatic protest.

Twenty years or more have passed since Kurloff first observed certain vacuoles or cell enclosures in the protoplasm of the large mononuclear leucocytes of the guinea-pig while working in Ehrlich's laboratory. Since then improved staining methods and discoveries in the field of protozoology have made it possible to take new view-points in regard to these cell enclosures which are called Kurloff's-bodies. Therefore it is not with surprise that we find Ferrata, Patella, Goldhorn, Schilling and others believing these bodies to be protozoan in nature. Patella however is the only one who claims to have observed a flagellate develop from a Kurloff-body and of course this observation would put an end to all dispute if it could be verified.

For general purposes, especially in haematological work, the Giemsa method, based on the Romanowsky principle, is certainly the most satisfactory stain for Protozoa. For certain structures, however, and in general as a control of the Giemsa stain, it is always necessary to have at one's disposal another method which will give particularly clear pictures of the nuclear elements (see e.g. Minchin, 1909). Of the different methods which are employed for this object the iron-haematoxylin stain is probably the most valuable and the most frequently used. There are, however, several circumstances which are unfavourable to its use as a universal stain. Its principal disadvantage is, that a differentiation is essential: the preparation is first deeply over-stained and the colour is afterwards extracted to the degree which is deemed convenient in each particular case. This extraction is always somewhat irregular, so that the observation, especially of intra-corpuscular parasites, is sometimes made very difficult, and it is not often possible to obtain in a single specimen a satisfactory stain of all the different elements. This difficulty is enhanced by the fact, that the red blood-corpuscles generally retain a deep grey, or almost black, colour. Further, a rather serious drawback is that in sections where greater masses of blood, and particularly blood-clots, are present, it is almost impossible to distinguish either intra- or extra-corpuscular parasites; to make such masses of blood transparent it is necessary to differentiate so much, that the nuclei are also decolourized. A certain inconvenience is also experienced because of the long duration of the staining process, at least 30 hours when the original Heidenhain's method (1896) is adhered to; and although the more recent modifications, especially that of Rosenbusch (1908), have to a great extent overcome this difficulty, they still suffer from the two other disadvantages referred to.

Although in nature Sleeping Sickness is chiefly transmitted by Glossina palpalis, the possibility of other modes of infection has been suggested by various authors.

1. The parasite described inhabits the alimentary tract of two species of Lucilia. In addition it has a resting stage—the ‘cyst’—which is passed in the voided excrement of the insect.

2. When the cyst is ingested by a fly it grows in length and becomes flagellated in the ‘crop’; in the midgut it greatly elongates and multiplies rapidly by division; in the hindgut it first shortens, then becomes spherical, and finally oval and cyst-like, meanwhile losing its flagellum.

3. The cysts measure 3 μ, the fully flagellate forms 20 μ, in length.

4. The cysts possess a cytostome and cytopharynx, the functions of which are probably nutritive.

5. The flagellum consists of two parts (i) a cytoplasmic part, which probably subserves the power of movement and which I therefore propose to call the kinetoplasm, and (ii) a thread of chromatin secreted by the rhizoplast.

6. The function of the chromatin in the flagellum is probably to sustain a filamentous form.

7. The nucleus divides by a definite process something akin to mitosis.

8. The chromidia serve as reserve material for the supply of chromatin in the cell. They are secreted probably by cell-plastids.

9. I propose the name of this parasite be Herpetomonas luciliae, and that the genus Herpetomonas should be defined so as to include the forms described as Leptomonas.

In a recent paper (1911), Swingle describes some stages of the life-history of (1) Trypanosoma lewisi in Ceratophyllus fasciatus and Pulex (sp.?), and (2) a new species of Herpetomonas (“ H. pattoni ”) found in these fleas.

The life-cycle of S. gallinarum may be briefly summarised as follows:

Commencing with the ordinary parasite in the blood of the fowl, the spirochaete grows until it reaches a certain length (16 μ–19 μ) and then divides by the peculiar mode of transverse division described above. This process is repeated and is probably the only method of multiplication of the parasite within the blood. When the spirochaetes disappear from the circulation some of them break up into coccoid bodies which, however, do not usually redevelop in the fowl. When the spirochaetes are ingested by Argas persicus, some of them pass through the gut wall into the coelomic fluid. From this medium they bore their way into the cells of the various organs of the tick and there break up into a number of coccoid bodies. These intracellular forms multiply by ordinary fission in the cells of the Malpighian tubules and gonads. Some of the coccoid bodies are formed in the lumen of the gut and Malpighian tubules. The result is that some of the coccoid bodies may be present in the Malpighian secretion and excrement of an infected tick and when mixed with the coxal fluid may gain entry into another fowl by the open wound caused by the tick's bite. They then elongate and redevelop into ordinary spirochaetes in the blood of the fowl, and the cycle may be repeated.