28 
Journal of Agricultural Research 
Vol. I, No. i 
devour sheep, it is quite likely that T. ovis also occurs in coyotes and other 
wolves as well as in dogs. In view of the fact, however, that dogs come 
in much closer relations with sheep it seems quite evident that dogs are 
chiefly responsible for the transmission of the parasite to sheep. It is 
possible though rather unlikely that the tapeworm occurs in other carni¬ 
vores than dogs and wolves. There is little likelihood that the parasite 
is transmissible to man, and for all practical purposes its nontransmis- 
sibility to man may be considered an established fact. No such tape¬ 
worm has been reported from man, and, moreover, there are no authentic 
cases of the occurrence in man of any dog tapeworm belonging to the 
genus Taenia. Furthermore, Chatin has noted that the swallowing of 
muscle cysticerci from sheep failed to result in infestation in his case. 
The present writer, as already noted, has likewise on three occasions 
swallowed live and active muscle cysticerci from sheep without resulting 
infestation (p. 26). 
Following the ingestion of the eggs of the tapeworm by sheep, the 
parasites reach the muscles in less than 13 days; they either do not pass 
through the liver or, unlike Cysticercus tenuicollis , leave no trace of their 
passage through this organ. In less than three months (83 days) the 
cysticerci reach their full development. As early as seven weeks after 
the ingestion of the cysticercus by a dog, its development to the mature 
egg-producing tapeworm may be complete. The development therefore 
appears to be somewhat more rapid than in the case of Taenia hydatigena , 
which was found by Teuckart (1856a) to require from 10 to 12 weeks. 
No doubt, however, the period required for development is subject to 
great variation, and though seven weeks is perhaps near the minimum 
for T. ovis , the period very likely may be greatly prolonged, as has been 
noted by Hall (1911, p. 510) in the case of the gid tapeworm. 
ZOOLOGICAL DESCRIPTION OF THE SHEEP-MEASLE PARASITE 
Taenia ovis (Cobbold, 1S69) Ransom, n. comb., 1913. 
1869: Cysticercus ovis Cobbold, 1869a, p. 30, fig. 2 (in Ovis aries; England). 
1873: Cysticercus ovipariens Maddox, 1873a, p. 245-253, pi. 18, figs. 1-15, 17-18, pi. 19, fig. 1 (in Ovis 
aries ; England). 
1878: Cysticercus cellulosae of Kiichenmeister, 1878, in Kiichenmeister and Ziim, i878-i88ia, p. 104 
(apparent misdetermination of C. ovis; in Ovis aries; Germany). 
1885: Cysticercus tenuicollis of Chatin in Railliet, 1885a, p. 234 (apparent misdetermination of C. ovis; 
in Ovis aries; France). 
1886: Cysticercus oviparus Leuckart i886d, p. 498 (for C. ovipariens). 
1913: Taenia ovis (Cobbold) Ransom, 1913. 
Specific Diagnosis of Taenia. 
Larval stage .—An oval cysticercus (PI. II, fig. 1) 3.5 by 2 mm. to 9 by 4 mm. in 
diameter. Head and neck invaginated from the wall of the caudal bladder not at 
one end but about midway between the ends. Membrane of bladder very thin; 
with small mammillate projections; not corrugated transversely (fig. 5 and fig. 6, a). 
Neck transversely corrugated, coiled spirally when invaginated, 1 to 5 mm. long when 
evaginated. Head 500 to 800/* in width; suckers oval, 240 to 320/1 in diameter; rostel- 
