Sarcosporidiosis in the opossum 
and its experimental production in the Guinea pig 
by the intra-muscular injection of sporozoïtes 
By S. T. DARI.IXG. 
'l'his SLibject is of spécial interest because of the host, Didcl- 
phis, it being the first recorded instance of the presence of sarco- 
sporidia in the opossum. It is of additional interest because the 
fresh sporozoites in saline solution after intramuscular inocula¬ 
tion into the tissues of a guinea pig took on an atypical develop¬ 
ment and produced sporozoa not unlike those found by the writer 
in man (i) and in the guinea pig (2) after feeding with sporozoites 
from Sarcocysiis mûris from the rat. 
A very unusual distribution of the sarcosporidia vas noted, tor 
they were found in the connective tissue, smooth muscle, intesti¬ 
nal tract, lungs, glandular tissue, and in the heart, as well as 
striated voluntary muscle, the latter being the usual location of 
sarcosporidia. It should be noted here that Wasielewski (3) re¬ 
marks that in onlv one instance were sarcosporidia found in loca¬ 
tions other than muscle, and that was in the submucosa of the in¬ 
testine in the Kangaroo. It is of peculiar interest that sarcospori¬ 
dia, having this very unusual distribution in the intestinal tract, 
should apparently be confinée! to the Marsupialia. 
It will be recalled that Blanchard classifiée! this sporozoon ac- 
coreling to the location of the parasite, i. e., striateel muscle, or 
connective tissue, into the familv Micschcridae in which the pa¬ 
rasite was situated in the striateel muscle, and into the family Bal- 
bianidae, in which the parasite is situated in the connective tis- 
stie. This classification, of course, has not held, for as Braun 
(1) Darling, s. T., Sarcosporidiosis with Report of a Case in Man, Arch. 
of Internai Medicine, 190g, III, 183. 
(2) Experimental Sarcosporidiosis in the Guinea Pig- and Its Relation to a 
Case of Sarcosporidiosis in Man ; Journal of Experimental Medicine, vol. 
VII, No. I, 1910. 
(3) Sporozoenkunde, Jena, 1896, p. 119. 
