40 THE INTERNAL PARASITES OF 



administration of beef measles to a low~class Mahom- 

 medan syce, and also to a Hindoo boy, lie succeeded 

 in artificially rearing the Taenia mediocanellata. These 

 human bearers were, it seems, perfectly willing to 

 play the part of host to a class of guests which most of 

 us contemplate with aversion. The interest of this 

 experiment, however, lies less with the circumstances 

 attending its conduction, than with the practical issues 

 associated with its success. In particular, we have here 

 afforded us incontestable proof that the beef tapeworm 

 requires a period of twelve weeks for its perfection, 

 as such; and thus also is confirmed a truth that I 

 had long previously maintained and enforced on other 

 than experimental grounds. From professional data 

 alone I have repeatedly been enabled to predict how 

 long it would take tapeworms to re-form in human 

 bearers after their more or less incomplete evacuation as 

 the result of treatment. Different tapeworms severally 

 require unequal periods for their full maturation ; but 

 at present we are only acquainted with the amount 

 of time consumed in the case of those forms which have 

 been made the subject of experiment. It would be very 

 interesting to learn how many months are requisite to 

 complete the development of the long tapeworm of the 

 ox and sheep ; the more so, since it only requires six 

 weeks for the perfect development of the hydatid- 

 forming tapeworm of the dog (Tcenia echino coccus). 

 These practical points merit further consideration. 



It is not very easy to convey to any person unfamiliar 

 with parasites an accurate idea of the singular appearance 

 presented by an ordinary beef tapeworm when removed 

 entire from the host and spread out at full length. Philo- 

 sophically speaking, we have in such an entozoon a chain 



