432 M. Siebold on the Transformation of the 



I had only been able to establish by the comparison of the Cysti- 

 cercus fasciolaris of rats and mice with the Taenia crassicollis of 

 cats ; but neither M. Kuchenmeister^s experiment nor the con- 

 sequences to be deduced from it were satisfactory to physicians 

 and naturalists. He was charged with having published his ex- 

 periments before they could be considered properly terminated. 

 The discussion which arose on every side on this question was by 

 no means calculated to throw much light on the subject, espe- 

 cially as M. Kuchenmeister did not appear to have sufficient 

 knowledge of helminthology to be able to affirm positively the 

 identity of the species indicated by him. This has determined 

 me to go over the subject again^ making use especially of young 

 dogs, and causing them to swallow not only the Cysticercus pisi- 

 formiSj but also the C. cellulosus and tenuicollis, the Ccenurus ce- 

 rebralis, and the Echinococcus veterinorum. In this work I have 

 been zealously seconded by M. Lewald, my pupil. The following 

 results were obtained with Cysticercus pisiformis. 



These cystoid worms, the size of which did not exceed that of 

 a pea, and which were still contained in the cyst of the intestinal 

 membrane, were introduced by means of milk into the stomachs 

 of some young dogs, to the number of from thirty to sixty indi- 

 viduals to each. These dogs were then killed by means of chlo- 

 roform at various intervals of time, and the contents of the 

 stomach and intestines carefully examined, when the worms 

 which had been swallowed as food were readily observed in 

 various states of development. 



Two hours after they were swallowed, all the cystoid worms 

 still remained in the stomach, but in most cases the cysts in 

 which they had been enveloped had disappeared ; at the same 

 time most of the worms which had been deprived of their cyst 

 had also lost their terminal vesicle, which had either been di- 

 gested or still adhered in fragments to the abdominal extremity. 

 All the worms found in the stomach, whether with or without 

 their vesicle, had the head and neck withdrawn into the body. 



Three hours after ingestion there were no longer any worms 

 in the stomach ; they had all passed with the chyme from this 

 organ into the small intestine. Then, after having lost their 

 cyst and terminal vesicle by the digestive action of the stomach, 

 they all, without exception, as though feeling themselves at home, 

 had again pushed out the head and neck. In all, a distinct 

 lesion was perceptible at the abdominal extremity, at the point 

 where the terminal vesicle had existed. 



In dogs killed several days after the ingestion of the Cysticerci, 

 these worms were found greatly increased in size ; the largest 

 had attained a length of 3 inches, the smallest of 1 inch. The 

 body, at first merely wrinkled transversely, now distinctly ex- 



