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.

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.

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.

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.

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.

1. In accordance with the views held by Chatton and Alilaire (1908) and by Roubaud (1909), I have seen that a true trypanosome-stage occurs in the life-history of Crithidia calliphorae. These try-panosomes have an undulating membrane and cannot be considered as herpetomonads with their blepharoplasts situated behind the nucleus and a completely internal flagellum (Woodcock), nor are they herpetomonads with the flagellum bent back along the body of the cell (Mackinnon). This existence of a trypanosome stage in the life-history of Crithidia is quite comprehensible if we consider that in many cases true Trypanosomata are changed into Crithidiae when they pass from the blood into the gut of an invertebrate host (T. gambiense, T. lewisi, Schizotrypanum cruzi, etc.).

2. There is no sharp difference between the genera Crithidia and Herpetomonas. In Crithidia calliphorae forms may be observed without any trace of an undulating membrane (Diagram I, Fig. 1); in Herpetomonas calliphorae such an organellum may be sometimes present (Diagram IX, Fig. 4).

Still I think that it is not permissible to throw these two genera together, as, generally speaking, an undulating membrane is present in Crithidia and absent in Herpetomonas.

3. Herpetomonas is often biflagellate, even when no signs of cellular division are present and the flagellates multiply less actively than in monoflagellate stocks. Still I agree with Patton that this biflagellate condition is too inconstant to permit of its being recognized as of generic significance.

4. The structure of the blepharoplast of Herpetomonas is distinctly like that of a nucleus, with peripheral chromatin and one or more central granules. It is true that the behaviour of these granules during the division is not so regular as that of the karyosomes of real nuclei, nevertheless, I think that the aspect of the blepharoplast of H. calliphorae is a strong argument in favour of Schaudinn's, and also Minchin's, view that this organellum must be regarded as a specialized nucleus (kinetonucleus).

5. The flagellum of Crithidia calliphorae is constructed in the same way as that of Trypanosoma lewisi: a basal granule is present and the new flagellum is formed by the production of a new flagellar root by fission of the basal part of the old flagellum. In Herpetomonas calliphorae a basal granule (at the base of the flagellum) and a marginal granule (at the point where the flagellum reaches the surface of the cell and becomes free) are present. The part of the flagellum situated between these two granules is the rhizoplast. The marginal granule first divides; then follows the fission of the rhizoplast and basal granule; lastly, from the marginal granule a new flagellum grows out, so closely entangled with the old one that it often seems as if the production of the new flagellum occurs exclusively by fission.

6. The extranuclear chromatoid granules of H. calliphorae consist of volutin. They are numerous during the preflagellate stage and disappear gradually during the flagellate stage; in the post-flagellate stage they are few in number or altogether absent.

This behaviour suggests that volutin in H. calliphorae may act as a sort of nutritive reserve-substance. In degenerating individuals the volutin granules become extremely numerous, an abnormal condition observed also in Trypanosomata (“ volutinosis ”). Consequently volutin seems to play the double part of a nutritive substance, and product of degeneration; this, however, likewise holds for many other nutritive substances (fat, glycogen, etc.).

7. The blepharoplast of H.'calliphorae shows cyclical changes. During the formation of the post-flagellate stages the achromatic substance is lost and only the chromatic portion remains. The blepharoplast is smallest at this period. The preflagellate stages possess a larger blepharoplast, and this organellum reaches its maximum dimensions during the flagellate stage. I am not able to say whether or not these cyclical changes have any special importance; perhaps they have something to do with the regulation of the normal relation between nucleus and protoplasm.

8. H. calliphorae was observed by me only in the gut of the fly and does not seem to be transmitted hereditarily, as is the case in Crithidia melophagia (Swingle, 1909; Porter, 1910).

The observations recently set forth by Dr Leiper, and by Dr Sambon in a discussion, have led us to re-examine the ova of S. japonicum in the material which we have at hand. This material was described previously by one of us together with a report of some comparative measurements of the ova of this species of trematode furnished by Dr Shiga.

(1) About 30% of the O. moubata from Uganda have been found to be immune to infection with S. duttoni.

(2) When infected ticks are kept at ordinary temperatures (about 21°C). the following parts of the body are found to harbour the infection :—gut + contents, sexual organs, Malpighian tubules, excrement.

The following parts were found to be uninfective:—salivary glands, coxal fluid.

(3) When infected ticks are kept at a temperature of about 35°C. for two or three days previous to dissection, all the organs of the body, including the salivary glands, are found to be infective. Moreover the incubation periods that elapse before the appearance of spirochaetes in the injected mice are shorter than in the case of the corresponding experiments with ticks that had not been kept at a high temperature.

(4) No spirochaetes have been detected in any of the organs of infected ticks that had been kept at a temperature of about 21°C. When a tick ingests blood containing spirochaetes, the latter persist in the lumen of the gut for periods varying from a few days up to as long as four weeks; usually, however, they disappear from the gut in the course of nine or ten days.

(5) When infected ticks are heated to a temperature of 35°C. for two or three days, spirochaetes reappear in the lumen of the gut, and also appear in all the organs of the tick, and in the coelomic fluid.

(6) The spirochaetal infection that may follow the bite of an infected O. moubata results from the entrance of the infective material, excreted by the tick whilst feeding, into the open wound caused by the tick's bite. It is not the result of the inoculation of infective material from the salivary glands.

In a recent number of Parasitology, Miss Porter, under the above heading, complains because, in the Zoological Record for 1909 (Protozoa division, p. 60), I put the generic names Crithidia and Herpetomonas in inverted commas, when applied to certain species; on this ground she charges me with allowing my personal opinions to influence me in my compilation of the Record, my opinions being, according to her, “extreme and decidedly opposed to the opinions of those who have worked personally on the parasites in question.” Incidentally, Miss Porter makes it appear that my opinions are extreme and of little or no value.

Through the courtesy of the Editors of Parasitology I have been favoured with an advance proof of the remarks of Dr Woodcock on a former note of mine relating to the procedure of the Recorder of the Protozoa section of the International Catalogue of Scientific Literature and the Zoological Record. In my article I raised three points. (1) In certain cases where the generic names Crithidia and Herpetomonas were placed in inverted commas in the Catalogue, I stated that no direct evidence existed to justify such a procedure. (2) I protested against such meddlesomeness on the part of the Recorder. (3) I stated that the Recorder, who had not worked on the parasites themselves, held, consequently, extreme views. Dr Woodcock's so-called reply has afforded me considerable amusement and it is a matter of surprise to me that he has been so ill-advised as to write such a poor rejoinder—he must know that he has made no answer to my remarks. That the weakness of his position is well known to him is shown by his recourse to the tactics of vituperation and innuendo, where he remarks that my method of criticism is “not straightforward but, on the contrary, distinctly oblique.” Dr Woodcock has no case and so has adopted metaphorically the old, old method of “abusing the plaintiffs attorney,” in the shape of discussing my own papers on parasites not originally under discussion. I am sorry that one who apparently claims to be an authority is reduced to such second-rate methods. While I regret the necessarily severe character of this, my rejoinder, it is impossible to deal otherwise with the numerous side issues raised by Dr Woodcock.

So far as I have been able to find, very little work, if any, has been done to ascertain the resistance of ticks to the gases usually employed in fumigation. This is probably because fumigation for the destruction of ticks is not, under ordinary conditions, a practical method. There recently arose, however, a question at Lourenço Marques (Portuguese East Africa), as to whether ships bringing cattle from Madagascar could be cleaned of the ticks which might have dropped from the cattle and be thus rendered clean for use in the transport of clean cattle for breeding purposes. The port authorities possessed a “Clayton Fumigating Apparatus” for use in disinfecting plague-infected ships and it was suggested that this system be tried for the purpose. Several tests were accordingly carried out with the co-operation of the Chief of the Veterinary Service, the Port Doctor, Municipal Officer of Health, and several local medical men. The “Clayton” being a standard system of fumigation, I will not enter into a discussion of it.

A precise knowledge of the geographical distribution of Ornithodorus moubata is very desirable, as it bears directly upon the distribution of the Relapsing Fever of Tropical Africa. It therefore appears desirable to publish the accompanying map and a list of places showing the distribution of the tick. Both the map and the list are, however, of necessity far from perfect.

In Parasitology, Vol. III. p. 486, there is a description by F. M. Howlett of the paraffin boxes in use here for preserving pinned insects. As the description of these boxes is incomplete and not quite correct, it seems desirable to add a description which will enable others to make these boxes. We use teak boxes, of a standard size, well varnished within; when the varnish is dry, a piece of cork carpet cut to fit the box and previously enamelled white above, is laid ready to hand, a mixture of paraffin wax (melting point 136° F.) 80% and flake naphthaline 20% is kept melted and a small quantity is run into the box; the cork carpet is at once put in, and rolled down on the melted mixture which sets and holds it; more of the liquid is then run in, sufficient to cover the cork completely; this sets with an even smooth surface (the box being on a perfectly horizontal surface), and the box is ready when cold. This method has not only been tried but we have nearly 2000 boxes in use and are replacing all our papered boxes. To all who may wish to preserve insects in one place I recommend these boxes, but they are too heavy if one is moving and for that a lighter paraffined box is required.