83 
ON A NEW SACCHAROMYCETE MONOSPORELLA 
UNICUSPIDATA gen. n. nom., n.sp., PARASITIC IN 
THE BODY CAVITY OF A DIPTEROUS LARVA 
(■DASYHELEA OBSCURA WINNERTZ). 
By D. KEILIN, Sc.D. 
(From the Quick Laboratory, University of Cambridge.) 
(With Three Text-figures.) 
The genus Monospora (= Monosporella renamed 1 ) was founded by Metschni- 
koff in 1884 to designate a parasitic fungus which he discovered in Daphnia 
magna. This monocellular fungus, of which he described only one species, 
Monospora bicuspidata 2 , lives free in the body cavity of its host, where it 
multiplies actively by budding in a yeast-like manner (Fig. I, l, 2 , 3). 
hen the body cavity of the host is entirely invaded by the parasites, 
these grow in size, become elongated, and form club- or sausage-shaped asci 
in each of which is developed a single needle-like spore having both ends 
pointed (Fig. I, 4, 5 and 6). When the parasitized host dies, it is filled with 
ripe spores, and healthy Daphnias, which feed on the detritus of their dead 
and diseased fellows, become infected by ingesting the asci. The latter, when 
they enter the host’s alimentary canal, set free the needle-shaped spores 
which perforate the gut wall and penetrate in the body cavity (Fig. I, 8) 
where they germinate laterally, thus starting the new infection (Fig. I, 7). 
Metschnikoff s studies on this parasite afford a striking instance of the 
phenomenon of phagocytosis. In his lectures on inflammation (1893, pp. 83- 
84), it is stated that directly the spore “appears outside the intestinal wall, 
it is attacked by leucocytes, which are carried to the spot by the blood-stream. 
The cells fix themselves on the spore, forming around it a collection of cells, 
which often fuse together into a plasmodium, which causes the spore to undergo 
a series of remarkable changes. On being enclosed in the leucocytes the spore 
1 The generic name Monospora, given by Metschnikoff to the parasite, is invalidated for the 
reason stated in the Appendix to this paper, p. 90. 
2 The species of Monospora, discovered by Metschnikoff, was described by him under the name 
M. bicuspidata, and under this name it is referred to in his various publications, nevertheless all 
the authors I have consulted (Zopf, Hansen, Dangeard, Guillermond, Lafar, Saccardo) wrongly 
name the species M. cuspidata Metschnikoff. I do not know who changed the specific name, but 
incline to the view that the error may have arisen through a misprint or misquotation, none of 
the authors mentioned having apparently referred to Metschnikoffs original papers. 
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