CROSSOBOTHRIUM LACINIATUM. 43 



7. In both scolex and proglottids of fresh specimens many 

 clear, transparent, thread-like muscle fibers may be seen. There 

 will also be found an abundance of clear, rounded granules of 

 lime. 



8. Watch the movements of the large, detached proglottids. 

 Pull proglottids from the posterior end of the specimen to see how 

 easily they may be detached. Very many tape-worms have these 

 "motile proglottids," which in some cases remain alive for so long 

 after being detached as to seem almost like independent animals. 



Mount stained specimens of proglottids in balsam and study 

 the reproductive organs. 1 



1. On one side of the proglottid the lateral genital aperture 

 will be seen. The penis is a long, slender organ, found pro- 

 truding, or lying in its sheath near the lateral aperture. The 

 vas deferens, a long, convoluted tube, extends from the penis 

 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. 



1 Specimens may be killed in the manner described for Bdelloura. 

 Enough pressure should be used to flatten the proglottids decidedly. 



