ORIGIN OF CYSTICA AND CESTOIDEA. 59 



1. EXPERIMENTS OF FEEDING WITH CYSTICERCUS PISIFORMIS. 



The cystic entozoon, known by the name of Cysticercus 

 pisiformis, is a very common inhabitant of the liver and peritoneum 

 of hares and rabbits. Cysts as large as a hazel-nut are frequently 

 disseminated completely through the substance of the liver of 

 hares, and these cysts are not unfrequently found hanging down 

 like bunches of grapes from the external surface of the liver ; in 

 rabbits the great omentum and the mesentery are generally full 

 of these cysts. Commonly such a cyst only contains a single 

 Cysticercus pisiformis ; but two are also sometimes enclosed in a 

 common cyst. In Breslau, the rabbits which were sold in the 

 markets in the spring months of 1852 were almost invariably 

 infested by this Cysticercus, whence I made use of them at the 

 Physiological Institution in that place for my feeding experiments. 

 The results of these experiments were published in the inaugural 

 dissertation 1 of my pupil, Dr. Lewald, who took a very active share 

 in them ; subsequently I gave some account of them myself in the 

 1 Zeitschift fur Wissenschaftliche Zoologie/ Bd. iv, 1853. The 

 number of Cysticerci which I administered at once in these experi- 

 ments was various, seven, twenty, forty, and sixty. In all cases, 

 the Cysticerci were left enclosed within their cysts, and in these 

 experiments, as in all subsequent ones, I wrote down in my 

 journal, the precise time of feeding, the number of the cystic 

 worms made use of, and the dogs fed with them, subjecting these 

 last, after feeding, to strict watching and careful attention. 



Of experiments tried with Cysticercus pisiformis upon ten 

 dogs, the following are the results, which I repeat from the report 

 I made in rny essay in the Zeitschift cited above. When the 

 encysted Cysticerci are devoured, it is the cysts which are first 

 attacked by the gastric juice in the dog's stomach, and then the 

 caudal vesicle is consumed ; but not, however, the remaining part 

 of the Cysticercus, so that of the whole Cysticercus pisiformis 

 nothing more is left than the whitish round body which was 

 enclosed in the caudal vesicle, and which consists of the head and 

 neck of the animal involuted within its body, or, in other words, 



1 This dissertation appeared at Berlin in 1852, under the title <De Cysticercorum in 

 Tsenias metamorphosi pascendi experiments in institute physiologico Vratislavensi 

 administrates illustrata.' 



