158 Coccidia parasitic in man 
bodies; nor did they, at this time, propose any name for them. They appear, 
however, to have regarded them as closely similar to the coccidia found in the 
intestinal villi of carnivores (dog, cat, polecat, etc.); that is to say, to the 
organism now generally known as Isospora bigemina. But they add that “the 
contents'’ of their human parasites “was sufficiently unlike” these. 
A little later, Railliet and Lucet (1891) return to the coccidia of the Carni¬ 
vora and accept the name then just bestowed upon them by Stiles (1891),— 
namely, Coccidium bigeminum. But they propose to subdivide the species 
into varieties corresponding to the different hosts in which the parasites had 
been found. The form in the dog they name C. bigeminum var. canis ; that in 
the cat, var. cati; that in the polecat, var. putorii; and they add that there is 
perhaps a fourth, var. hominis, in man. Strangely enough, however, they 
make no mention of their own discovery in this connexion, but state that 
hominis “corresponds to the form observed by Kjellberg.” 
Railliet (1895), however, a few years afterwards, states that Kjellberg’s 
parasite was probably Coccidium bigeminum (p. 146); and on another page 
(p. 140) he says that the forms found in human faeces by Railliet and Lucet 
probably belonged also to the same species. 
It would appear, therefore, that Railliet and Lucet discovered two human 
cases of infection with an organism which they believed to be similar to 
Isospora bigemina of divers carnivores; that they identified it with the parasite 
previously found by Kjellberg; and that they proposed tentatively to name it 
Coccidium bigeminum var. hominis. The identity of Railliet and Lucet’s 
parasites is, nevertheless, not beyond dispute. It is, in fact, impossible to 
recognize them as coccidia from their description alone. We have only the 
authors’ opinions unsupported by any cogent facts; and the dimensions of 
their “coccidia '* seem, at first sight, to contradict their hypothesis that the 
human parasites which they discovered could be a variety of Isospora bi¬ 
gemina. It is clear from their accounts, however, that—like other workers at 
this time—they did not understand the morphology of the “bigeminate” 
coccidia of carnivores. The two spores within the oocyst were regarded as two 
separate “coccidia”; and the measurements which they record relate, accord¬ 
ingly, in every case to the sporocysts—not the oocysts—of the parasites 1 . It 
is therefore possible that their human parasites, in spite of their apparently 
very small size, may really have been closely similar to Isospora bigemina. 
SilcocJc’s case. The only case of human hepatic coccidiosis described in 
England has been recorded by Silcock (1890). The patient was a woman aged 
50 who died at St Mary’s Hospital, London, in 1889. The chief symptoms 
noted before death were enlargement of the liver and spleen, fever, and slight 
diarrhoea. At the autopsy the liver was found to be “much enlarged,” and to 
contain “a number of caseous foci arranged in groups,” each of them sur¬ 
rounded by “a well-marked red ring of inflammatory congestion." The spleen 
1 See Railliet and Lucet (1890, 1891) and Railliet (1895). 
