ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 



55- 



twelve accessory collecting: tubes, each joined by a group of three 

 capillaries — the " 2 by by ;! " type. Tiie light thrown on affinities by 

 the excretory system is discussed. J. A. T. 



Eg-gs and Miracidia of Human Schistosomes. — William W. 

 CoRT {Univ. California Pi/blicntions, Zoology. 1911), 18, 50i)-519,. 

 7 figs.). In Schistosoma mansoni the position of the miracidium within. 



Miracidium of S. mansoni, from glandular surface ; ad, anterior ducts ; 

 ap, anterior papilla ; eg, cephalic gland ; exp, excretory pore ; /, flame 

 cell ; gc, germ cell ; n, central nervous mass ; rd, rudimentary digestive 

 sac. 



the egg may be either with the anterior papilla toward the spine or 

 away from the spine. The shell is very tough and resistant. When 

 liberated the miracidium swims actively, rotating on its long axis. 

 Penetration into the intermediate host may be facilitated by the 

 secretions of the large uniceUular cephalic glands. These may dissolve 

 the tissue or neutralize the secretions of the host. The central nervous- 



