ANIMAL PARASITES. 59 



sufficient room in the embryonal vesicle, but is pushed out of 

 it. The same thing is seen in the Cysticercus fasciolaris of the 

 mouse, except that in this the central body is jointed. However, 

 I will by no means assert that there may not be cestoid embryos 

 which proliferate at the hinder part. It is possible, as we saw in 

 the preceding note, that Von Siebold's notion of Stein's cestoid 

 worm is correct, and then, in this case, the embryonal booklets 

 would not have been cast off, but have remained seated upon the 

 anterior part of the body, whilst the development of the head 

 would have taken place at the posterior extremity, and the 

 anterior part of the body of the embryo become converted into 

 that sterile appendage which we usually denominate the caudal 

 vesicle. In this case, it is true, the embryo must have turned 

 itself round, and, after taking firm hold, have pushed its abdomen 

 forward towards the ventral cavity, and retracted the anterior 

 part of its body towards the intestine. However, even in this 

 case, the booklets would not be transmitted to the tsenioid period 

 of existence. 



Proliferation on the posterior part of the body of the cestoid 

 embryo will, however, be regarded as impossible by no one who 

 takes into consideration the multiple proliferation of the Ccenuri 

 and Echinococci. The latter takes place on such various parts, 

 that we cannot say it occurs on the anterior or on the posterior 

 part, but it takes place everywhere in the body of the embryo, 

 which consequently cannot arrive at the formation of a true 

 caudal vesicle. 



Unfortunately, we can state nothing more definite regarding 

 the spot in the embryonal vesicle on which it proliferates the 

 T&niae, called by Leuckart bladder-tape-worms, in which we are 

 here especially interested. The booklets are so small that 

 they are overlooked, or small folds of the skin easily imitate 

 them. Even here, however, it is most probable that they are 

 not cast off and imbedded in the enveloping cyst. If Leuckart's 

 statement, that the small booklets could be found in the vicinity 

 of the anterior extremity of the body, at a distance of Ol millim. 

 from the cephalic pit, in a Cysticercus pisiformis of 2 millim. in 

 diameter, should be confirmed, then the Cystic, pisiformis, and 

 perhaps the other true Cysticerci, would belong to that first kind 

 in which the proliferation takes place at the head. 



If, from the experiments made by Haubner and myself, by 

 Leuckart, Roll, Van Beneden, Eschricht, Gurlt, May, and others, 



