34 ANIMAL PARASITES. 



in water for ten days, but is usually devoured by them at once, 

 I nevertheless undertook the direct investigation of this question. 

 I laid Cystic, pisiformes with their enveloping cysts in water, and 

 as the temperature was that of a hot summer I placed them in 

 an ice-cellar, in which an average temperature of 8° R. (=45° F.) 

 was shown by the thermometer. A stay of a few days in this 

 place was sufficient to render all the Cysticerci pisiformes inca- 

 pable of development in the intestine of the dog, although this 

 vesicular worm thrives in that situation much more readily than 

 the Cysticercus cellulosae employed by May, even if this ever finds 

 a suitable dwelling-place in the intestine of the dog. 



From the concordant experiments of Haubner and myself, of 

 Leuckart, Van Beneden, and Moller, this much is established : 



1. Mature Taeniap have hitherto been reared successfully from 

 all vesicular worms administered when a suitable host was se- 

 lected ; thus from Cysticercus pisiformis the Taenia serrata vera 

 was obtained ; from Cyst, tenuicollis the Taenia ex Cyst, tenuicolli 

 (erroneously named T. tenuicollis by Moller aud the Danish 

 committee of examination, this name having been already em- 

 ployed by Rudolphi for a Taenia of the marten and weasel, the 

 Cysticercus belonging to which I found in the liver of the field- 

 mouse and mole =r Cysticercus innominatus Hyperdcei, Leuckart) ; 

 and from Ccenurus cerebralis the Taenia Ccenurits, all three in the 

 intestine of the dog ; from Cyst, fasciolaris the Taenia crassicollis, 

 in the intestine of the cat ; from Cyst, celluloses the Taenia solium, 

 in the human intestine ; from Echinococcus veterinorum [scolici- 

 pariens, Kiich.) a Taenia Echinococcus, in the intestine of the 

 dog ; and from Cysticercus longicollis Hyperdaei, the Taenia 

 crassiceps, Rud., in the intestine of the dog (Leuckart). Moller 

 in vain swallowed Cysticerci tenuicolles with the view of infecting 

 himself with a Taenia, and Zenker and mvself administered 

 Echinococcus altricipariens to dogs ; in the latter case, however, 

 it is possible that the individual scolices were already dead. 



2. From the eggs of Taenia solium in pigs, from those of 

 T. Ccenurus in sheep and cattle, of T. serraia vera in rabbits, of 

 T. crassicollis in rats and mice, of T. ex Cysticercus tenuicolli 

 in sheep and lambs, the corresponding vesicular worms have 

 been reared. The experiments with the eggs of the Taenia of 

 Echinococcus have hitherto remained unsuccessful. 



The phenomena which occur after the different administra- 

 tions are so constant that we may almost predicate by days and 



