TRANSLATIONS AND SELECTED ARTICLES. 375 



"We may notice, also, the circumstance that certain physiologists are 

 accustomed to administer worms at several doses, and at more or less 

 distant intervals — a course which allows of all kinds of interpreta- 

 tions. Lastly, we must not leave out of account the unsuccessful 

 results, which have not always been recorded. 



" But, let us not delay with these logical considerations ; let us see 

 what experiment teaches, which is alone competent to pronounce a 

 positive judgment. 



" We will, once for all, state that we have taken the greatest pre- 

 caution to induce precision in our experiments. Thus, when we have 

 sought to implant Caenuri of the sheep into other animals, we have 

 not been content simply to administer them en masse, as has been 

 done by various experimenters. In order to obtain accurate results, 

 we have determined, on every occasion, the number of the heads or 

 gcolices which have been given, by which means we have been able to 

 decide, with unusual precision, with respect to certain results which, 

 in any other way of proceeding, might have led us to erroneous con- 

 clusions. Again, whenever we have made use of these same scolices, 

 we have taken pains to assure ourselves that their development was as 

 far advanced as possible, and that they were actually alive. 



" Physiologists have grievously erred in not giving comparative 

 tables, showing the length of their experiments, and the size of the 

 Entozoa which they have found. The consequence is, that we some- 

 times observe inexplicable differences in the length of the Entozoa 

 found on inspection after death. 



"In a dog which had been made to swallow some Caenuri sixteen 

 days before, we found a certain number of Taeniae not more than 

 2 millimetres long, whilst others were 20. After a similar interval of 

 time, an experimenter even obtained some Tanniae which had reached 

 the length of 80 millimetres. In another case, at the end of twenty- 

 three days, we found in one and the same dog, Taeniae 4 millimetres 

 long , and others, which had reached the enormous length of 60 centi- 

 metres. Is it possible that the scolices of the Caenuri implanted on 

 the same vesicle, having the same degree of development, and abso- 

 lutely of the same age, after having been introduced into the intestine, 

 should exhibit, in so short a time, such a prodigious difference of size, 

 from 4 to CO millimetres ? It is inconceivable. If we had followed 

 the usual plan, and administered Caenuri at differemt times, such a 

 result would apparently have afforded an evident demonstration. 



