C. Dobell 
187 
Wenyon and O’Connor (1917) fed kittens and a mouse on the ripe spores, but 
none of them became infected. Subsequently O’Connor made a very carefully 
controlled experiment with two young puppies, but he was unable to infect 
either. Attempts of this sort are not easily carried out, as both puppies-and 
kittens are frequently found in nature already infected with a species of 
Isospora of their own. Up to the present, therefore, there is no evidence to 
show that /. hominis can parasitize any host but man. 
(2) Eimeria wenyoni n. sp. 
Eimeria (Coccidium) Wenyon, 1915 b. 
Coccidium (Eimeria ) Wenyon, 1916. 
Eimeria sp. Dobell, 1917. 
Eimeria sp. Dobell et Stevenson, 1917. 
Eimeria, Roche. 1917. 
(See Plate VIII, fig. 2.) 
1 have named this species in honour of its discoverer, who has given us the 
only description which we possess of the parasite 1 . It is possible, however, 
that the coccidia found in man by Eimer (1870) were of this species; and if so, 
then this is the organism which Rivolta (1878) named Cytospermium hominis, 
and to which other names have since been given. We have previously decided 
to regard Eimer’s coccidia as Isospora however, so that it will suffice merely 
to note this possibility here. It will be unnecessary to add a long list of con¬ 
jectural synonyms. 
This species is known only from its oocysts, which are similar to those of 
E. fale if or mis 2 . They are passed in the faeces in a fully developed condition, 
with the spores and sporozoites already differentiated. (Cf. fig. 2, PI. VIII.) 
The oocyst is approximately spherical, with a diameter of about 20/x. Its 
outer surface is rough and rugose, its inner smooth and lined with a delicate 
membrane. The four spores which lie within it are oval, and measure about 
10/z by 7/x. The external surface of the sporocyst is rough and irregular 
(probably from the presence of adherent remains of the epispore). There is no 
oocystic residual body. Each spore contains two typical sporozoites, lying 
with their blunter ends directed towards opposite poles, and one or two highly 
refractile masses (sporocystic residua). 
Wenyon (1916) found this coccidium in small numbers in a sample of faeces 
from a single case out of 556 whose faeces he examined. The patient was among 
those invalided to England from Gallipoli (in 1915) suffering from “dysentery ” 
or intestinal derangement, and was No. 242 in the series of cases studied at the 
London Hospital. In completing the examination of this series—775 cases in 
all—no other infections with this organism were discovered (Dobell and 
Stevenson, 1917): nor was its presence in the faeces recorded by any other 
1 The description of the organism here given is taken from Wenyon’s account (l!U5 6). 
3 The oocysts of E. falciformis are, however, typically somewhat oval, and not spherical. 
