266 SPERMATOGENESIS AND OOGENESIS ikss. 



(a, a, and d^— d^), and so forming a daughter colony which 

 becomes detached and swims freely in the interior of the 

 parent colony (a), by the rupture of which it is finally 

 liberated. In sexual reproduction certain cells enlarge and 

 take on the characters of ovaries (b, cny, ovy', my", ovy"\ 

 and Fig. 66, 6) the protoplasm of each forming a single 



Fig. 65. 



Part of a Volvox-colony showing the structure in greater detail than 

 in Fig. 64 : s, spermaries ; o, ovaries. (From Lang.) 



ovum : the protoplasm of others divides repeatedly and 

 forms aggregations of sperms (b, spy, spy, spy", and Fig. 

 65, s). By the conjugation of a sperm (f) with an ovum (g) 

 an oosperm (h) is produced, and from this by continued 

 division a new colony arises. 



Volvox is clearly comparable to a hollow polyplast, and 

 further resembles the higher or multicellular animals in that 

 certain of its cells are differentiated to form true sexual 

 products. 



It is necessary, in conclusion, to remind the reader that 



