680 DESCRIPTION OF THE BOTHRIOCEPHALID^E. 



lately led to another view of the nature of these structures. We now 

 know that in all tapeworms, and not only in the Bothriocephalidse, 

 numerous extremely fine tubules, hitherto unobserved, are attached 

 to the greater vessels, originating separately from the latter, extend- 

 ing undivided close under the surface of the body, and ending, after 

 a longer or shorter course, in a small goblet-shaped enlargement 

 (0-008 O'Ol mm. long, by 0'004 mm. broad). The opening serves 

 for the reception of large cell, rich in protoptasm, and on this is 

 seated a cilium which hangs freely into the funnel. These cells are 

 probably the proper secretory organs. They represent, according to 

 Pintner, a system of unicellular glands, whose secretion flows through 

 a more or less long, capillary, efferent duct to the tubular apparatus. 



The ciliated lappets, which have been repeatedly described by 

 earlier observers (p. 302), are all to be referred to these ciliated 

 funnels. In the vessels themselves structures of this kind are never 

 present. The earlier opinion to the contrary originated in an 

 illusion, occasioned by the presence of ciliated funnels above or below 

 the vessels. 



A terminal vesicle is present in the Bothriocephalidae only in the 

 young stage, before any segments have been separated off. Afterwards, 

 the longitudinal vessels seem to open independently, as is (according 

 to Pintner) the rule also in Taeniadae. There are, however, numerous 

 observations as to the presence of special marginal pores, by which 

 the longitudinal ducts open to the exterior through short transverse 

 vessels. Pintner describes such openings in Caryophyllceus and 

 Tricenophorus, and Fraipont in various Scoleces and in Bothriocephalus 

 punctatus. In the last, these "Foramina secundaria" exhibit a 

 certain degree of regularity, being usually situated in twos or at most 

 fours, at the base of the several segments. With this agrees Kiehm's 

 observation, according to which, in Schistocephcdus (as I have been 

 able also to convince myself), an excretory aperture lies on the right 

 and on the left side of every segment. 



The Generative Organs exhibit peculiarities to which we have 

 already called attention (pp. 308, 317), distinguishing them clearly from 

 the Taeniadse. These peculiarities may be, for the most part, traced 

 to the fact that the uterus, instead of being closed, as in the Taeniadse, 

 opens externally by a special aperture. The presence of this uterine 

 aperture not only permits of an early liberation of the ova, but also 

 of a continued functional activity, which of course further pre- 

 supposes that the generative organs (and especially the yolk-gland) 

 possess a very considerable development, and persist throughout their 

 life in complete integrity, while in the Taeniadee they degenerate 

 after the passage of the ova into the uterus. 



