84 Tlie Sunfish as a Host. 



that, for example, shown at fig. 3 in the accompanying tinted 

 plate — is not one individual animal, but in reality a series of in- 

 dividuals associated together so as to form a long band resem- 

 bling an ordinary measuring tape, the likeness to the latter 

 gaining strength by the circumstance of the band being jointed, 

 or transversely marked at tolerably regular intervals. Every 

 tapeworm is, in point of fact, a colony of creatures arranged in 

 single file, and in the more technical nomenclature of helmin- 

 thology is termed the " strobila." As we have recently taken 

 occasion to remark elsewhere, the tapeworm, or " strobila," is 

 usually composed of several hundred joints, each segment re- 

 presenting a single member of the colony, and to this latter we 

 apply the term " proglottis." Those individual ' ' proglottides" 

 which are nearest to the lower end, or so called tail of the 

 ordinary tapeworm, are sexually mature; moreover, they are 

 hermaphroditic, that is, they are provided with both male and 

 female reproductive organs. Those feebly developed joints, 

 which form the so-called neck of the worm, are imperfect or 

 immature individuals, whilst the little head is neither more nor 

 less than a single joint or proglottis, curiously modified and 

 furnished with an apparatus by which the strobila or colony is 

 securely anchored to the interior of the infested "host." 



It is necessary that the above-mentioned facts be borne in 

 mind, otherwise the true relation of the parts of the strobila or 

 tapeworm to be presently described will be entirely lost sight 

 of; and it becomes the more necessary to insist on these dis- 

 tinctions in cases where, as in the present, the application of 

 our zoological nomenclature seems to lend countenance to the 

 popular and erroneous notion that the strobila is, after all, only 

 one zoological individual. So far as tapeworms are concerned 

 our specific distinctions for the most part depend upon the cha- 

 racters presented by the so-called head of the worm ; but this 

 head is, as we have seen, the primary individual of the colony. 

 It might be supposed that although the head of one kind of 

 tapeworm-colony differed from that of another kind, yet the 

 joints or members of the colony might display similar cha- 

 racters in different strobila, and so be after all the same 

 creatures, although their so-called heads were different. Such 

 a notion, however — which at one time was practically supported 

 by Yon Siebold himself when he denied the hitherto recog- 

 nized specific distinctions of five well marked tapeworms 

 (Band und Blasenwurmer, p. 98 et sea.) — is contra-indicated 

 by numerous facts ; for even the joints themselves exhibit co- 

 ordinating structures, which are found to be invariable in the 

 different tapeworm colonies. 



The more complex the characters of any particular class of 

 animals, the greater the confusion introduced into the writings 



