;-J7,S I- IJTMA AND T, KURIMOTO. 



.segmerjt. lUit this process seems not to take place unilornily 

 throughout, as indic:ited by the fact that primary segments, with and 

 without proglottides undergoing (juaternary division, showed no 

 reofularity in their order of succession, and also bv the fact that some- 

 times, between two more or less typical primary segments, there were 

 interposed two or more proglottides, which showed no ti-ace of division 

 and were separated from one another by boundaries as marked, and 

 hence presumably as old, as those that 1)ounded any primary segment. 

 At all events, the generally accepted idea that in a tape-worm the 

 more posteriorly situated proglottis is always the older, seems not to 

 hold tiaie in the present species of Bothriocephaliis. The repeated 

 serial di\ision here described naturally reminds one of a somewhat 

 similar process in MicnMomwn and certain annelids, but we abstain 

 here from entering into comparisons. We regret that Fig. 11, Plate 

 XVIII, which should represent a portion of sample No. 1, has failed 

 to ilhistrate exactly the ordinal distinctions of proglottidal boundaries 

 plainly visible on the real object. 



How far backwards in the entire tape- worm the subdivision of 

 proglottides is repeated, coidd not be ascertained further than that it 

 probably ceases with the beginning of tlie development of genital ducts, 

 somewhere between the two portions represented liy onr samples Ko. 1 

 and No. "2. In the latter, in which the formation of sfenital ducts is 

 almost completed, abortive proglottides before described are plentifully 

 met with. One might regard these as indications of divisions taking 

 place here, though certainly only external, were it not for the 

 fact that similar abortive proglottides are also found in sam])le 

 No. 3 or No. 4 in about the same jiroportion. Hence, we nither 

 consider all those present in our samj^les No. 2-4, as representing the 

 proglottides that were formed about the time when the genit:d ducts 

 were beginning to develo])e but too late to develope their own. 



