DR. T. S. COBirOLD ON CESTOID ENTOZOA. 175 



Simauds received (froia Messrs. Caudwell, of St. Neots) the head 

 of a " giddy " sheep which had been killed two days previously. 

 Ou examination the brain was found to contain a perfect poly- 

 cephalous hydatid {Gcenurus cereiralis) which, it was estimated, 

 supported about 150 scoleciform processes, or larval tapeworm- 

 heads. It was removed entire, and given by Mr. Simonds to a 

 dog, which swallowed the parasite readily in its unbroken condi- 

 tion. Only five days subsequently, namely on the 20th of March, 

 the experimental animal was destroyed ; and here again a com- 

 plete success attended our experiment. A careful examination 

 of the alimentary mucus enabled me to extract a large number of 

 extremely minute tapeworms, of so small a size that they were 

 scarcely visible to the naked eye. Though only the heads and 

 necks were developed, their characters corresponded with what 

 was hitherto known of the head and neck of Tcenia coenurus, to 

 which species they were undoubtedly referable. Their number 

 appeared to correspond precisely with the number of scoleces 

 attached to the common " gid " vesicle ; but no attempt was made 

 to collect every specimen, as that would have involved an immense 

 amount of unnecessary labour. All trace of the vesicle common 

 to the colony of "heads " had disappeared, the necks of the sco- 

 leces, detached by digestive action, having become rounded off and 

 more or less pointed (according to the degree of contraction shov.n 

 by each specimen while under microscopic examination). 



Exp. 2. On the 6th of April, 1865, a similar administration, 

 with a brain-hydatid furnished with about 100 cephalic processes, 

 was performed on a stray dog. Two days subsequently, however, 

 the animal was claimed by its rightful owner, and we had there- 

 fore, in this instance, no opportunity of ascertaining the result of 

 our experiment. 



Exp, 3. On the 25th of April Mr. Simonds received (from Mr. 

 Mackinder, of Peterborough) the head of a sheep affected with 

 " gid." The brain was found to contain three T. coenuri. One of 

 these, furnished with numerous heads, was given to a large half- 

 bred lurcher dog. On the 16th of the following May the animal 

 was destroyed, thus permitting twenty-one days for the develop- 

 ment of the slow-growing Tcenia coenurus. As too often happens 

 in the case of old dogs, the digestive passages were found loaded 

 with a great variety of tapeworms ; nevertheless it was here 

 again quite easy for us to distinguish between the parasites which 

 had been introduced by our experiment and those which liad 

 gained access to the cauine "bearer" without our aid. Thus 



