While examining the strongyles of the fourth stomach of an ewe belonging to the Cambridge University Farm, which had been slaughtered for post-mortem examination, numerous male and female Ostertagia circumcincta (Strongylus cervicornis of MacFadyean) were found. A few specimens of Haemonchus contortus were also present.

Habitat. This marine leech, a member of the Rhyncobdellida, or jawless leeches, is parasitic on the angler, Lophius piscatorius, and, in my experience, attaches itself to the skin of the fish on the ventrolateral surface indiscriminately; it is not found near the vent, as is usually the case with Pontobdella, which occurs frequently attached near the cloaca of the skate.

This peculiar larval form of cestode, parasitic in man, was first discovered in a Japanese woman (Case I) on 9. vii. 1904, and described by Prof. Ijima in 1905. Subsequently it was found in an American by Dr H. Gates, of Manatee, Florida, in June, 1907, and described by Dr Charles Stiles, who had received Gates' specimens for identification on 25. v. 1908. In the same year in which Gates' case was recorded, we observed a second case (Case II) in Japan. In this case an enormous number of worms were present and they were generally larger than those from the former Japanese and American cases. Recently a patient suffering from the same form of cestode larva (Case III) was found in the Dermatological Institute of the Imperial University of Kyoto.

On examining fresh specimens of white rats' blood containing numerous trypanosomes of a strain (T. brucei group), for which I am indebted to Dr J. W. Scott Macfie and with which I was experimenting at the Medical Research Institute at Yaba, Nigeria, I was struck by the energetic way in which the parasites attacked the red blood corpuscles. They sometimes adhered to the corpuscles for a long time, moving them about in different ways, and sometimes appeared to pierce their membrane, now in one place, now in another, penetrating more or less deeply into their substance. A careful search of a number of stained films revealed in some the presence of very interesting appearances which seem to establish the important fact that these trypanosomes are capable of ingesting and digesting erythrocytes. The accompanying figures, which are all from one and the same specimen taken six days after intraperitoneal infection, show that the parasite encircles the erythrocyte, which gradually becomes enclosed in its protoplasm, probably in a sort of vacuole which develops between the two nuclei. The erythrocyte becomes more or less disintegrated and gradually reduced in size; its characteristic staining remains for a long time recognizable, but the final result is a vacuole with homogeneous, almost unstained contents, between trophonucleus and kinetonucleus.

The results of the above described experiments suggest that Abderhalden's reaction may be of use in the study of protozoal diseases.

In the case of East Coast Fever it is seen that in early stages of the disease only the lymphatic and suprarenal glands seem to be affected, whilst in later stages destruction of tissue takes place in practically all the organs, and this corresponds with the results of microscopical examinations of the various tissues.

Various experiments were performed with dogs infected with Babesia canis, but in most cases, owing to the presence of haemoglobin in the serum, the controls gave positive results as well as the organs + serum. The blood of a dog taken at the commencement of the infection was found to contain substances having a destroying action on liver tissue, but not on the other organs employed, whilst in later stages of the disease practically all the organs were affected.

Whilst engaged in the study of the life-histories of certain Nematode parasites of domestic animals, I have had the opportunity of examining the alimentary tracts of a number of sheep and lambs obtained from various localities in England during the last 12 months, and have thus been able to collect and identify a considerable number of the parasitic Nematodes which are found so abundantly in this situation.

In a paper published with Warburton in 1909 (Parasitology, ii. 70–76, Figs. 17–26), I described and figured a number of abnormalities observed in ticks of which the most remarkable were two specimens, Boophilus decoloratus ♂ and Rhipicephalus sanguineus ♂ (Figs. 22, 25 and 26), showing two ani together with a duplication of the adanal shields; in the Rhipicephalus duplication was more pronounced in that a subcircular spiracle was present posteriorly in the median line; the Boophilus exhibited two caudal spines. The other specimens figured were Hyalomma aegyptium ♂ and Boophilus australis ♂ (Figs. 18 and 21) which showed underdeveloped adanal plates on the right side. All of these specimens were found attached to a host.

In Ticks (Part ii. p. 314) various cases are cited by me in which Ixodes in the larval, nymphal and adult stages have been found lodged beneath the skin of the host: Dubreuilh (1838), Van Beneden (1883) and Blanchard (1891) record cases in man where ticks were found either in a pustule or in cysts beneath the skin. In Blanchard's case a living I. ricinus (♀), 8 mm. in length, was excised from the patient, in whom it caused a subcutaneous tumour about the size of a nut which had appeared some weeks before. Mégnin (1867 and 1892) found (?) ricinus nymphs beneath the scabs covering pustules on the legs of a horse at Versailles. Kossel, Schütz, Weber and Miessner (1903) state that ricinus nymphs and larvae occasionally bore themselves beneath the skin of cattle.

Whilst engaged in rearing a number of bed-bugs, the variation recorded below was observed in an individual that had just moulted from the first to the second nymphal stage. As such an abnormality does not appear to have been previously described, it seemed worth while to place it on record.

In the course of an investigation into the tapeworms of poultry, I came across a minute form (Amoebotaenia sphenoides von Linstow) hitherto unrecorded from this country, and incompletely described from the few specimens examined by other workers. Its economic importance remains to be ascertained but, pending a complete experimental treatment of its life-history, I submit an account of its anatomy.

In these days of close research into the activities and the anatomy of various insects, it is surprising that the structure of the common, indeed almost ubiquitous, Bed Bug, Acanthia (Cimex) lectularia, has so long escaped the thorough investigation which is called for by the standards of modern science.

Many herpetomonads have been recorded from various insects belonging chiefly to the Diptera and Hemiptera, but until the present instance, members of this genus of flagellates have not been found in the Mollusca and very few in other Invertebrata. Also the habitat of the herpetomonads has usually been either the main alimentary tract or the haemocoel of their hosts. Digestive glands hitherto have not been recorded as being infected.