96 Transactions of the Royal Canadian Institute [vol. x. 



clearly defined by the contents being highly stained by counterstains 

 such as Orange G. In spite of the readiness with which these capillaries 

 can be followed through the subcuticula, it was found impossible to trace 

 them far towards the centre of the strobila, much less to connect them 

 with any of the main excretory vessels. In the cortical parenchyma, 

 however, they seem to unite to form a quite compact plexus, the diameters 

 of the tubes of which vary from 2 to 6/i. In the foremost joints there are 

 more foramina secundaria on the anterior portion of the proglottis than 

 on the auricular ring ; while very few are to be met with in the scolex. 



Generative Organs. 



There is a more or less definite point in the strobila, at or about the 

 15th proglottis, ahead of which the genital organs do not seem to develop 

 and behind which in older strobilas they appear very quickly. For 

 instance, in one strobila 96mm. long and containing 55 joints, only the 

 beginnings of the vitelline follicles are to be seen in the 14th joint; more 

 and a few testes in proglottis 15; no appearance, in sections, of the 

 generative ducts in the median line in the 14th; a mass of nuclei around 

 the median excretory vessels (from transparent preparations) in 15; 

 and an uterus full of eggs in 16! One must look then to the younger 

 strobilas in which the proglottides are yet immature to see the earliest 

 stages in the development of the reproductive organs, especially of the 

 ducts. Here, of course, the stages are more gradual. 



The genital ducts develop from a long, more or less cylindrical anlage 

 surrounding the posterior half or two-thirds of the median excretory 

 vessel, as shown in Figs. 15 and 16, which are from transparencies of 

 proglottides 16 and 17, respectively, of a young strobila. Soon after the 

 earliest traces of it can be seen in transparent preparations, the anterior 

 end enlarges to become later the anlage of the cirrus-sac and entrance to 

 the vagina, while the posterior end gives rise to the ovaries and organs 

 of the "generative space", including the "uterine tube". From the 

 middle part arises the " uterine sac", vagina and vas deferens. 



All of the ducts seem to develop lumina almost simultaneously, but 

 the vagina and cirrus do not pierce the ventral wall of the proglottis until 

 somewhat later. Even the uterine sac approaches the ventral surface 

 at its posterior end in the early stages. During the necessarily brief 

 study of the development of the genital ducts the writer was able to 

 corroborate, in general, the finds of Young ('13) and Schaefer ('13) as 

 to the manner of formation of the lumen and epithelium from the synci- 

 tial anlage. Further remarks on the possible fate of the epithelial nuclei 

 during the formation of the cuticle in the distal portions of the ducts will 

 be met with below in connection with the more detailed description of the 



