Whilst working through the collections of Nematodes at the Punjab Veterinary College in Lahore I had the opportunity of examining a number of Strongylid worms from the Indian camel (Camelus dromedarius) belonging to two species, labelled Haemonchus longistipes and Nematodirus spathiger, respectively.

Although some of the earliest work on the Strongylid parasites of horses was done by Giles in India in 1892, the subject has been almost completely neglected in this country since that date; even the comparatively recent list of Indian parasites compiled by Gaiger (1910) makes no attempt to differentiate the numerous Nematodes which had been confused under the names Sclerostomum equinum and S. tetracanthum until the appearance of Looss' famous monograph in 1902.

1. Copulation between individuals of the two species O. moubata, and O. savignyi may occur, and the stimulus of coition may induce oviposition, the eggs being non-fertile.

2. There is no evidence of parthenogenesis in this species, nor do these ticks undergo ecdysis after reaching maturity.

3. An increase in temperature of 8° C. from 22° C. (a) doubles the.rate of oviposition, (b) decreases the fertility of the eggs by 30 per cent., (c) reduces the longevity of the female tick from 715 to 397 days, i.e. by 40 per cent, and (d) approximately halves the period required for metamorphosis, under laboratory conditions. Under these conditions at 37° C., reproduction is inhibited, and the longevity of the female is reduced by 80 per cent.

4. An individual may undergo from four to eight ecdyses before reaching maturity, the great majority of the males appearing after the fifth ecdysis and the females about equally after the fifth and sixth ecdyses.

5. Engorgement can take place one or two days after emergence, at any stage, the average time required being three-quarters of an hour. There is great variation in the extent of engorgement at each stage, but this is not correlated with the ecdysis period. The largest meal may be taken either before or after an individual reaches maturity.

6. Moisture has an adverse influence on the vitality of the individual, excess of moisture inhibiting growth.

7. An approximation to the stage of development attained can be made after the study of the structure of the hypostome, leg and spiracle. The larval and first four nymphal stages are fairly well differentiated, much more so than the later stages, but variation due to nutrition requires further study.

It is a common experience that mosquito larvae when they are brought into a laboratory to undergo their development, often fail to develop normally. At times a high mortality takes place, or the larvae lapse into a condition of suspended development continuing as larvae for months. The latter phase usually ends in death before pupation can take place. I have been puzzled to account for these manifestations for a very long time, and have conducted various experiments in the hope of discovering the cause. The general opinion on the matter, I think, is that there is “something wrong with the food supply,” but as a matter of fact larvae supplied with an ample diet often show the same state of affairs.

A consideration of the above experiments, and of the available literature dealing with the distribution of trypanosomes and tsetse flies in nature, has suggested certain general conclusions which will now be put forward.

As stated in a slip inserted opposite the first portrait-plate of this series, the collection herein presented is issued without regard to chronological order, moreover, the portraits are confined to those men of science who, in various ways, have advanced the subject of parasitology.