OEIGIN OF CYSTICA AND CESTOIBEA. 73 



dog were only ten inches. This unequal development of the 

 T<enice within the same period of time is probably to be ac- 

 counted for by some special peculiarities of the circumstances 

 into which, in these cases, the scolices of the Ccenurus cerebralis 

 had been conveyed. 



There is yet another remarkable phenomenon which was 

 brought to light by the experiments on feeding with Ccenurus 

 cerebralis. It is that in each separate case, worms, of a very 

 dissimilar stage of growth were produced, although every indi- 

 vidual dog had been fed only once with scolices of Ccenurus 

 cerebralis. This diversity in the growth of the scolices conveyed 

 at the same period of time into the same intestine, may, perhaps, 

 originate in the various stages of development of the scolices 

 at the time of their introduction. It is known that the parental 

 vesicles of the Ccenurus go on growing without intermission, 

 and that fresh scolices are, by the process of budding, continually 

 springing forth on their inner surface. Through these peculiar 

 conditions of the Ccenurus cerebralis, older scolices long since 

 perfected, and only awaiting the opportunity of further develop- 

 ment, were conveyed into the dogs' stomachs, together with 

 younger ones, some of them only just formed, some, again, not yet 

 fully developed. From this point the older scolices proceeded 

 rapidly to their further development, and to the generation of 

 proylottides, whilst the younger scolices grew more slowly, and 

 the youngest forms, whose gemmation was not yet quite com- 

 pleted, were, probably, incompetent to pass from the stomach 

 into the small intestines of the dog, but yielded to the digestive 

 powers of the former. 



EXPERTMENTS ON FEEDING WITH EcHINOCOCCUS VETERINORUM. 



The Echinococcus veterinorum, which is of such common 

 occurrence in the liver and lungs of our domestic cattle, does 

 not, probably, differ specifically from the Echinococcus hominis, 

 whose parent vesicle often attains such an enormous size in 

 the most widely different viscera of man, and by its growth 

 so obliterates the substance of the organs round about it, as 

 to bring about the death of its host. The experiments of feeding 

 with these worms which I made on twelve young dogs and a 

 young fox, I have already fully described. 1 For each experiment 



1 See the < Zeitschrift fur Wiss. Zoologie,' Bd. iv, 1853, p. 409, Taf. xvi, A, fig. 19. 



