48 PLATYHELMINTHES. 



to the testes, which form many rounded, deeply stained struc- 

 tures that lie about the oval outline of the uterus. On leaving 

 the penis the vas deferens extends toward the pointed end of 

 the proglottid, along the side of the uterus, until it reaches a 

 point anterior to it, where it may sometimes be seen sending 

 branches to the testes, but is frequently lost. Throughout its 

 length it is greatly convoluted and is generally filled with sper- 

 matozoa. 



2. At the base of the penis, in the lateral genital aperture, 

 is the external opening of the female organs. From this point 

 a small tube, the vagina, leads to a point below the sac-like 

 uterus, which is sometimes very large and sometimes collapsed 

 and small. The vagina ends in a small pouch, the ootype, from 

 which a short canal (sometimes visible, but more often obscured 

 by the vagina, which lies above or below it) leads to the uterus. 



3. The ovary consists of a large many-fingered mass in a 

 median position, near the posterior end of the proglottid. It 

 surrounds, more or less completely, the end of the vagina and 

 ootype. 



4. The vitelline glands occupy the posterior corners of the 

 proglottid and may extend anteriorly along its margins, by the 

 sides of the testes, nearly to its anterior extremity. The ducts 

 from the vitelline glands unite and join the ootype. 



5. The shell gland is a small median mass that is situated 

 between the lobes of the ovary around the ootype. 



From the lecture and figures, understand the relation of the 

 ducts of these glands and the vagina to the ootype and uterus, 

 how and where the eggs are fertilized, and how they are finally 

 lodged in the uterus. Why should hermaphroditism occur in 

 this form? 



Draw a figure of the proglottid showing all of the parts you 

 have seen. 



Larval Stage. Examine and draw a specimen of the larva 

 found in the cystic duct of the squeteague. The scolex with 

 its suckers at the anterior end, and the opening of the water- 

 vascular system at the posterior end, are readily seen. Compress 



