122 



THE IIELMINTIIES. 



§115. 



In the terminal, constricted portion of the utez-us, eggs, vitelline cells, 

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

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

 and by means of the Vesicida seminalis interior. The succeeding folds of 

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

 many vitelline cells. Their recently-formed 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 j 

 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 Carijophyllaejis,^-^^ these organs are repeated many 

 times one after another, having in the same individual diiferent 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 Ligula, 

 Triaertophorus, and Botkriocephalus, the uterus consists, exactly as in the 



Trematodes, of a 



very 



tortuous tube filled with oval eggs.'--' But in 



the posterior extremity of the body. Its position 

 is indicated, even vvhsn tlie penis is not protruded, 

 by a small papilla. 



With Octobothrium, and Polystomum, there 

 is a round muscular sac concaaled directly behind 

 this opening, which contains a circle of delicate 

 horny ribs, the lower extremities of which are 

 bifid and form a support like a bownet. Mayer 

 (Beitr. loc. cit. p. 21, Taf. III. fig. 3, 6) has seen 

 ten similar ribs with Octobothrium lanceolatiim. 

 I have found eight with Polystomum integerri- 

 mum, and forty with Polystomum ocellatum. 

 Their U33 is wholly unknown to ms. 



19 The eggs of the Trematodes have apparently 

 only a single envelojje. Among tlie 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 secreted by the walls of the uterus 

 (the Tuba Faliopii) at a time when the ovaries and 

 the secreting organs of the vitellus were inactive, 

 so that the substance of the envelopes was hard- 

 ened befjra receiving their usual c )ntents. With 

 Amphistomum subclavaturn, Octobothrium lan- 

 ceolatum, Polystomum intei^errimum, and ocel- 

 latum, an! Diplozoon paradoxum, 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 egis has been taken 

 for a testicle and penis ; see Nordmann Microgr. 

 Beitr. lift. 1, p. 73, Taf. V. VI. fig. 1, h.; also ^ogt, 

 in Muller's Arch. 1841, p. 34, Taf. II. fig. 11. 



The eggs of Monoslomum. verrucosum, and 

 some otiier sp'rcies of this genus which live in the 

 intestine of Chelonia esculenta, have 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. Hehninth. PI. VIII. 

 ^g. G, B. 3.* 



:;0 With Caryophyllaeus mutabilis, there is only 

 a single cirrhus-sac upon the ventral surface of tl»e 

 posterior body, and from which a delicate long 

 penis often protrudes. 



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

 segments of Bothriocephaluspunctatus, and Tae- 

 nia ocellata. As such, ought, perha))s, to be re- 

 garded those organs which Eschricht (Nov. Act. 

 Acad. Leop. XI.X. Suppl. 2, Tab. I. fig. 2, e, e) 

 has considered with Botkriocephalus latus to be 

 ovaries. Tlie organs secreting tlie vitellus are a 

 mass of irregularly arranged granulations situated 

 upon both the dorsal and the ventral surf ices, and 

 which have very fine excretory ducts. This mass, 

 called by Eschricht (loc. cit. p. 25, Tab. I. fig. 5) 

 the ventral and dorsal granules, cannot, together 

 with its excretory ducts, be made out, except wlien 

 filled with th'2 vitelline substance. With Taenia 

 ocellata, the vitelline organs are limited to the 

 sides of each segment, at the anterior border 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. 



22 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.] Sea also for the structure of p. 602, Taf. XX. fig. 17 (^Polystomum appcndi- 

 the genital organs Thaer, Muller^s Arch. 1850, culatum). — Ed. 



