ANIMAL PAEASITES. 35 



weeks what state of growth will be found. I should advise any 

 one wishing to repeat the latter experiments to administer the 

 eggs of T. serrata vera to young rabbits, even from motives of 

 economy. 



It only remains now to refer to the opinions which have 

 been entertained regarding the developed tape-worm-chains, as 

 they are called. Up to a very recent time it was the most 

 general opinion, still entertained by some, that this tape- 

 worm-chain was a simple animal, with numerous segments. 

 But, nevertheless, even some of the older physicians and 

 naturalists correctly perceived that the tape-worms were not 

 simple but compound animals. By many of the older medical men 

 the isolated segments of tape-worms were regarded as separate 

 individual worms; and what Dujardin has recently called pro- 

 glottides, are described by them in the tape-worms of the human 

 subject as " Vermes cucurbitini." Valisneri and Coulet, who 

 were subsequently followed by Blumenbach, to the horror of his 

 age, even described the tape-worms as animals composed of these 

 " Vermes cucurbitini." At the same time they fell into 

 the great error of not regarding this chain as produced by a 

 successive formation of joints placed one behind the other from 

 the head, but expressed the remarkable opinion that the tape- 

 worm was produced by the adhesion of the individual " Vermes 

 cucurbitini" one after the other, by which means the many- 

 jointed body of the tape-worm was formed. The idea that the 

 tape-worm was a compound animal was so completely repudiated 

 that S. Leuckart only ventured to express himself in the follow- 

 ing words : " I was almost inclined to think that I must also 

 regard the jointed tape- worms as organisms in which each joint 

 was to be considered an individual animal, and the whole, 

 therefore, as an ' animal compositum/ as indeed was previously 

 supposed by mauy distinguished zoologists." Eschricht first, 

 and after him Steenstrup, expressed this opinion more distinctly ; 

 and Van Beneden proved it more clearly by examples and 

 figures ; after Dujardin, as already observed, had described the 

 segments of tape- worms which occur isolated as peculiar animals 

 under the name of Proglottis. The Trematode-like appearance of 

 these last had already introduced errors in regard to their 

 signification. Thus Diesing described a proglottis of the Taenia 

 fimbriata of the Brazilian deer first as a Trematode, under the 

 name of Thysanosoma actinoides. Pallas, who had seen an 



