122 



THE IIELMINTIIES. 



»5>115. 



In the tcrmiiKil, constricte;! portion of tho uterus, eggs, vitelline cells, 

 and spermatic particles arc often found mixed together. It is probably here 

 that the eggs are formed, their fesundation occurring without copulation, 

 and by means of the Vesicula sembiaUs interior. The succeeding fjlds of 

 the uterus contain already, nicely-defined, oval eggs containing a germ and 

 many vitelline cells. Their rccontly-fornied envelope is still colorless, and so 

 thin and flexible, that the peristaltic contractions of the uterus give it a 

 variety of forms. But in passing from the uterus they lose this flexibility; 

 their envelope becomes more solid, — of a yellow and then a brown color; 

 and the whole, at the same time, undergoes a decrease in size, due prob- 

 ably to a condensation of their substance. The eggs of most of the Trema- 

 todes have an opercular opening at one extremity. '''■*' 



In the Cestodes, the walls of the genital organs are so very thin, and so 

 intimately blended with the parenchyma of the body, that their structure 

 and relations have not yet been well made out. 



With the exception of in Caryophyllaeus,^^^ these organs are repeated many 

 times one after another, having in the same individual different degrees of 

 development. They are always most complete in the posterior portion of 

 the body, being only rudimentary near the neck, while in the neck itself 

 they do not exist at all. In the articulated Cestodes, each ring contains 

 both male and female sexual organs ; and in their two Groups, the arrange- 

 ment of these is the same as in the Trematodes. It is probable that the 

 ovaries and the secreting organs of the vitellus are separate.'-^' In Ligicla, 

 Triaenophorus, and Bothriocephalus, the uterus consists, exactly as in the 

 Trematodes, of a very tortuous tube filled with oval eggs.*"* But in 



ths posterior extremity of the Ijody. Its position 

 is indicit'-vl, even whsn the penis is not protruded, 

 by a small papilla. 



With Octobothriiim, and Polt/stomum, there 

 is a round muscular sac cjncsaled directly behind 

 this opening, which contains a circle of delicate 

 horny ribs, the lower extremities of which are 

 bifid and fjrm a supjiort like a bownet. Mayer 

 (Beitr. Inc. cit. p. 21, T,if. 1I[. fig. 3, 6) has seen 

 ten similar ribs with Octobolhrium layiceolatum. 

 I have found eight with Polystomum inteserri- 

 mum, and forty with Polt/stomum ocellatum. 

 Their us3 is whiUy unknown to me. 



ly Th.' eggs of the Trematodes have apparently 

 only a siiigli envelope. Among the normal eggs in 

 the uterus may often be found others which are mal- 

 formed, also very irregular bodies of a yellowish or 

 brown color, formed almost entirely of the sub- 

 stance of these envelopes. These bodies were 

 most probably s3creted by the walls of the uterus 

 (the Tubi FMopii) at a time when the ovaries and 

 the secreting organs of the vitellus Vere inactive, 

 s) that the substance of the envelopes was hard- 

 ened bef)re receiving their usual c intents. With 

 Amphislom'im snbclavatum^ Octobolhrium lan- 

 ceolatum, Potystomum intrs^errimum, and ocel- 

 latum, and DijilozDon paraJoxum, the eggs are 

 very large, and in the last-named species their ex- 

 tremities are narrowed and lengthened into a spiral 

 filament, wherefore one of these eggs has been taken 

 for a testicle and penis ; see Nordmann Jlicrojr. 

 Beitr. Hft. 1, p. 73, Taf. V. VI. fig. 1, h.; also rogt, 

 in Midler's Arch. 1S41, p. 34, Taf. II. fig. 31. 



The eggs of Monoalomum verrucosum, and 

 some other species of this genus which live in the 

 intestine of Chelonia escu^e/ita, h?7e a very dif- 



ferent form ; they are oval and colorless, and at 

 each extremity have two papillae, which are grad- 

 ually developed into very long, sharp appendages ; 

 see Dujardin, Hist. Nat. d. Hehniuth. PI. VIII. 

 fig. G, B. 3.* 



-0 With Caryopliyllacus mutabilis, there is only 

 a single cirrhus-sac upon the ventral surface of the 

 posterior body, and from which a delicate long 

 penis often protrudes. 



iil I think I have seen an ovary in each of the 

 segments of Bothriocephalus punctatus, and Tae- 

 nia ocellata. As such, ought, perhaps, to be re- 

 garded those organs which Eschricht (Nov. Act. 

 Acad. Leop. XIX. Suppl. 2, Tab. I. fig. 2, e, e) 

 has considered with Bothriocephalus latus to be 

 ovaries. The organs secreting the vitellus are a 

 mass of irregularly arranged granulations situated 

 upon both the dorsal and the ventral surf \ces, and 

 which have very fine excretory ducts. This mass, 

 called l)y Esckricht (loc. cit. p. 25, Tab. I. fig. 5) 

 the ventral and dorsal granules, cannot, togetlier 

 with its excretory ducts, be made out, cxcejit when 

 filled with the vitelUne substance. With Taenia 

 ocellata, the vitelline organs are limited to the 

 sides of each segment, at the anteriui- b n-der of 

 which two main excretory ducts are easily seen ; 

 these form a single short canal in the middle of the 

 body. In this same place are two transversely- 

 placed oval sacs, and which are probably the two 

 ovaries. 



2'- The uterine convolutions are generally in the 

 middle of the body, and when filled with mature 

 eggs, appear through the skin as a brown rosette ; 

 see Eschricht loc. cit. Tab. I. II. (^Bothriocepha- 

 lus latus). 



* [ § 115, note 19.] See also for the structure of 

 the geoital organs Thaer, Mailer's Arch. 1850, 



p. 602, Taf. XX. fig. 17 (^Polystomum apperuii- 

 culatum). — Ed. 



