When beginning this investigation it was my intention to make a comparison between the anatomy of the apterous viviparous form and that of the winged viviparous form, to ascertain what differences were present corresponding with the difference in habit of the Aphis in these two stages. I found, however, that the literature bearing on the group to which S. rosarum belongs, was somewhat scanty, and as a rule, rather out of date. It therefore became necessary, before undertaking the comparative work, to obtain a somewhat more complete account of the general anatomy. It is with this idea in view that the following paper has been written; but, as will be seen on perusing it, much more attention has been given to the internal anatomy than to the external parts. It is my intention, now that this first part of the task is completed, to take up my original project. I desire to take this opportunity of expressing my gratitude to Professor Bridge, Mr A. E. Shipley, F.R.S., Mr Doncaster and Mr Collinge for the valuable assistance and advice they have given me whilst this work has been in progress.

A male Malay tiger was brought to the Clifton Zoological Gardens in July, 1908. He was then very thin and fed badly. After a time he settled down in his new quarters, and ate his food with greater relish. He appeared to be in good health and his coat was sleek and fine, but he never jumped or played in the usual way of his species. On February 4th he vomited, and had a severe attack of diarrhoea. His breathing became less abdominal and more thoracic in character, and death occurred two days later.

Amoeba chironomi, nov. sp., is distributed through practically the entire length of the digestive tract of the larva of Chironomus.

The body of A. chironomi varies from 15μ, to 18μ in length and from 10μ. to 12μ in breadth. The single pseudopodium may reach 15μ in length; one pseudopodium only is usually present.

Ectoplasm and endoplasm are well differentiated. A nucleus and a contractile vacuole are present. Food vacuoles are rare. The contractile vacuole resembles an iris diaphragm, consisting of a series of fine, curved, radiating canaliculi, opening into a central space. The excretory products are faintly reddish in colour. The presence of a contractile vacuole is uncommon in parasitic Amoebae.

The nucleus is poor in chromatin. A nucleolus is present.

A. chironomi is highly sensitive to the degree of concentration of the medium in which it lives. Very slight increase in density causes the organism to encyst.

Encystment occurs in the rectum of the host, and the cysts are voided with the faeces. The cysts are from 12μ. to 20μ long and from 9μ broad. The process of encystment is rapid.

The method of cross-infection of the host is probably a “casual” one, viz. by the mouth.

(1) The marked peculiarity in infection of Decapod Crustacea by certain parasites is the alteration of the sexual characters of the hosts (castration parasitaire of Giard). This has a twofold nature, viz.:—

(a) Sterility. In both sexes gonads dwindle and may entirely abort.

(b) Assumption of characters of other sex. In the male the external characters proper to the female are assumed in greater or less degree. The testis is transformed into a hermaphrodite gland, either while still infected by the parasite (incipient hermaphroditism of hermit crabs) or when freed from its influence (ripe ovotestis in spider crab). The reverse effects are not found in the female.

(2) This phenomenon occurs throughout the Invertebrata, but though sterility is a frequent consequence, the alteration of sex characters is never so definite as in the Crustacea. Analogous observations on parasitism in the Vertebrata have not been made.

(3) In the Insecta, parasitism appears to influence caste production. Grassi suggested that the sterility of soldiers and workers in Termites is due to protozoan parasites. In ants a giant caste is known (mermithergates) always harbouring a nematode worm.

Since we published our last notes upon new species, a considerable number of specimens have reached us from various parts of the world, thanks to many gentlemen who have interested themselves in these parasites. We propose to group our descriptions of new species according to genera as we progress with the diagnoses we are preparing for the work on Ticks which we are publishing in conjunction with Messrs Cooper and Robinson. We have already described several new species of Ixodes and Haemaphysalis and in this paper shall confine our descriptions to species belonging to these genera. Although, more recently, we have received many specimens belonging to the genus Ixodes, we have, in the majority of instances, been able to refer them to established species, but sometimes with great difficulty owing to the meagre description given by many authors, and especially to the absence of figures. We consider that too much stress cannot be laid upon the necessity of illustrative figures accompanying authors' descriptions of new species for a glance at a figure frequently suffices as a means of rapidly identifying a species, and for this purpose the simplest text figures are usually amply sufficient.

The natives of Siam are occasionally affected by subcutaneous tumours that have been found to be due to the presence of a small nematode worm named by Levinsen (1889) Cheiracanthus siamensis. Only one description of the species occurs in literature, and as this, the original one, was based upon a solitary immature female it is necessarily lacking in many details.

1. The alimentary tracts of 104 lice (Haematopinus spinulosus), which had been taken from rats infected with T. lewisi, were examined. In 51 lice no trace of T. lewisi could be found. In 53 lice T. lewisi, unchanged in every particular, was found in various parts of the gut. The trypanosome was seen to be quite unchanged in stained preparations.

2. The alimentary tracts of 45 fleas (Ctenophthalmus agyrtes), which had fed on infected rats, were examined. The T. lewisi could not be found at all in 43 fleas. They disappeared very rapidly from the ingested blood and could not be found in stained preparations. In 2 fleas trypanosomes were found, but they did not differ in form from those seen in the blood of the rat.

3. 263 lice were examined from rats which were apparently uninfected with T. lewisi. No form of T. lewisi was discovered in fresh or stained preparations.

4. 31 fleas from uninfected rats were dissected and their alimentary tracts examined. No trace of T. lewisi was found.

5. 15 lice were examined 18–48 hours after their removal from an infected rat. T. lewisi was found in 7 of these, but they shewed no developmental changes.

6. Observations made upon 36 lice from infected rats shewed that at the earlier stages of digestion T. lewisi was more often found than at the later stages. In some lice however trypanosomes could not be found at the early stages of digestion, although they were present at an advanced stage of digestion.

7. The examination of other organs than the alimentary canal in fleas and lice did not shew any form of T. lewisi.

8. Crithidia ctenophthalmi was found in 9 Ctenophihalmus agyrtes.

9. About 370 lice and 75 fleas were examined but no evidence was obtained of developmental changes of T. lewisi in either fleas or lice.

A large number of the trypanosomes and allied flagellates are now known to be the causal agents of some of the most fatal diseases of man and of the lower animals. The study of these parasites during the past fifteen years has truly made phenomenal strides, and at the present time it holds a position of commanding interest. Novy (1907) in a recent paper aptly states the reason for this active research when he says, “It is not merely because six or seven of these diseases have been recognised in domestic animals in Asia, Africa and South America. It is not wholly due to the discovery of a human form of the disease, but rather to the fact that the mastery by man of whole regions is called into question. The successful contest with malaria and yellow fever has now given place to the fight with trypanosomiasis and upon the issue of this struggle depends to a large extent the destiny of Equatorial Africa.”

In a recent paper Dr Sambon (1909) has made a violent attack on me for my gentle reminder to him that he has overstepped the boundary of established truths regarding the haemogregarines, and has let his imagination run wild. As he still persists in maintaining his position I feel I am bound to expose his methods, and in the present paper I propose examining in some detail his recent observations on the haemogregarines, and at the same time dealing with his reply to my paper.

1. We have discovered that Trypanblau and Trypanrot are highly efficient remedies in the treatment of canine piroplasmosis, no drug or mode of treatment having hitherto been found to exert any appreciable effect upon this very fatal disease.

2. The drugs exert a direct and observable effect upon the parasites (a) by causing the pyriform parasites to quickly disappear, and (b) in most cases, by causing the total disappearance of the parasites from microscopic observation in the peripheral blood.

3. The disappearance of the parasites from the blood is usually temporary, the parasites reappearing in small numbers after an interval of 9 to 12 days, but the dogs, as a rule, show no symptoms and gradually progress toward recovery. In our experience there is but slight loss of weight in treated animals, this being in marked contrast to what is usually observed in dogs which recover naturally. In the two dogs which died of a relapse the parasites reappeared after an interval of 4 to 5 days.

4. The experiments were conducted upon 21 dogs of all ages and of a variety of breeds. Many of the dogs were highly susceptible puppies. Twelve dogs were subjected to curative treatment, one dog received preventive treatment, and eight dogs served as controls.

5. Twelve dogs received treatment as follows:

(a) Two dogs were treated with Trypanrot and survived 111 days and 20 days respectively. In the latter case the dog was treated in an advanced stage of the disease, the parasites disappeared, and death appeared to be due to the after-effects of the malady.

Two control dogs died respectively on the 9th and 7th day after they were inoculated.

(b) Ten dogs were treated with Trypanblau and seven made a good recovery. Three of these dogs are still alive, having been respectively under observation for periods of 90, 83 and 65 days. Four of the recovered dogs died respectively of distemper on the 42nd and 43rd day, of severe mange on the 52nd day and of distemper and mange on the 69th day. We failed to cure the disease in 3 out of 10 cases treated: two small wormy ill-nourished puppies died from a relapse (on the 13th and 15th day) after they appeared to be on the road to recovery; one dog, treated only 3 hours prior to death, and when 50% of its corpuscles were infected, succumbed to the disease, but even in this case a visible effect was exerted upon the parasites by the drug.

Of the 7 control dogs, 6 died of piroplasmosis within 7–13 days after inoculation with virulent blood, and the remaining dog died of piroplasmosis on the 36th day after inoculation.

6. After the parasites disappear under the influence of the drug, the temperature usually falls to normal, but slight rises of temperature may at times occur, together with the subsequent reappearance of the parasites.

7. When the parasites reappear after treatment they occur in small numbers and can usually be detected only at the edge of the film. In such cases the parasites tend to occur in higher multiples [(PPPP) or more] within the individual corpuscles. The same appearance has been observed in one of the control dogs, which died of chronic piroplasmosis on the 36th day.

8. In the two puppies 10 and 11, in which death followed upon a relapse, the parasites reappeared after a shorter interval (4 to 5 days) than in any of the other dogs. The blood counts made during the fatal relapse are remarkable as showing a high percentage of dividing forms (D); that rapid invasion of fresh corpuscles was proceeding is also shown by the high percentage of single pyriform parasites (P) which occurred in the corpuscles.

9. One experiment is reported (Dog 13) in which Trypanblau was injected 24 hours after the animal was inoculated, with the result that no parasites appeared in the dog's blood up to the 65th day, and the dog remained perfectly well. The control dog died of piroplasmosis on the 7th day. (This experiment has since been successfully repeated.)

Further experiments of this character will be shortly reported upon.

10. Arsacetin and Soamin exert no curative effect upon canine piroplasmosis.