0. H. Treadgold 127 
presence of these facts I am unable to support the view that the central viscus 
represents the remains of the vitellus. 
Why this structure should be well developed in one species and poorly 
developed in another, is unknown. It is unknown whether the granules which 
enter into its composition have anything to do with the subsequent formation 
of the gut or not: whether they appear and disappear in a cyclical manner 
or whether—once formed—they persist until the larva dies or is taken up by 
the intermediate host, is also unknown. Under these circumstances it would 
seem premature to refer to these granules as consisting of reserve material. 
HI. General Biological Investigations. 
A. Various Parasites Observed in Papio cynocephalus. 
P. cynocephalus is a robust animal, the adult male weighing up to sixty 
pounds or more. Loa papionis was present ip ten, Microloa papionis in twelve 
of the fifty-five animals examined; but no other members of the family- 
either adults or larvae—were discovered. At the autopsy, the internal organs 
always appeared healthy, although various parasites were frequently present 
in considerable numbers. The following were noticed at one time or another, 
but their identity or otherwise with known species has not yet been deter¬ 
mined : 
Plathelminths. A cestode. 
Nemathelminths. Pliysaloptera, Agchylostoma, Oxyurus and Tricho- 
cephalus ; also a small unidentified nematode from an omental cyst. 
Arthropoda. The mesentery was often heavily infected with larval 
Porocephalus. 
Protozoa. Protozoa were not especially looked for. 
No Plasmodia were seen, but a small Trypanosoma was once noticed in a 
fresh preparation. It measured about 10/x in length, while its maximum 
breadth was 1*5 p. The undulating membrane was but feebly indicated and 
no projecting flagellum was seen; the macronucleus was a conspicuous object, 
being situated about the middle of the trypanosome. 
An unsuccessful attempt was made to cultivate the organism in Novy and 
McNeil’s medium. The inoculation of a small portion of clot under the skin 
of a mouse was also tried, but with negative results. Unfortunately the baboon 
had been destroyed before I thought of examining its lymphatic glands. 
» 
B. Eosinophilia in P. cynocephalus. 
Even in the most extensively infested animals a distinct degree of eosino¬ 
philia was never encountered, the differential leucocyte counts charted in 
Table V being typical. 
Parasitology xn 
9 
