22,2 Shaw: Merrillosphaera africana 205 



shows that the gonidia of the daughters almost all remain un- 

 divided until after the birth of the daughters. In some mothers 

 there are four daughters that form a group without room for 

 more behind. 



There is an abundance of sexual and male coenobia in some 

 material from the same source as specimens 16 to 24. The best 

 of this is mounted in Venetian turpentine and stained too lightly 

 for photomicrography. 



One sexual coenobium similar to those of typical Merrillo- 

 sphaera africana has five antheridia that are distributed in the 

 coenobium to form two pairs near the middle and an odd one 

 in a lateral position at the back. The arrangement is like that 

 of gonidia in an asexual coenobium. Each of these antheridia 

 forms a shallow cup of sperms or spermatogenous cells. 



A small sexual coenobium was noted in the same mother with 

 a somewhat smaller sister that contains two gonidia about 

 60 ix in diameter. This sexual coenobium contains twelve oogoni- 

 dia and three androgonidia, the latter all in process of division 

 and distributed like gonidia in an asexual coenobium, two in 

 the middle and one at the back. The paired ones are 2- and 

 8-celled, and the odd one is 4-celled. The oogonidia measure 

 about 32 p. 



Relatively mature oospores measure 35 to 39 ^ In these Ve- 

 netian turpentine preparations none of the spores show any 

 thickness of the spore wall. 



Mixture of sexual and asexual reproductive bodies in the same 

 coenobium was observed only once. In that case the coenobium 

 contains three daughters and five oogonidia. The daughters are 

 a pair in the middle and one at the back. Four of the oogonidia 

 are grouped in that hind quarter of the coenobium left vacant 

 by the lack of a mate to the smallest daughter. The fifth oo- 

 gonidium is in advance of the middle daughters. The mother 

 is 250 by 320 ^; the largest daughter is about 100 /x, and the 

 smallest about 75 p. The oogonidia range from 30 to 35 p. The 

 largest daughter contains four gonidia of from 18 to 22 ^ Its 

 mate is somewhat smaller and contains three gonidia. 



A SMALL FORM 



A small form that is sometimes mixed with other species and 

 sometimes forms almost pure cultures in the water has not 

 been fairly represented in the micrographs that have been made. 

 The only pictures of it are from the margins of plates used for 

 larger species. They happen to be from Pond Q in Pasay on 

 October 2, 1915. It is believed that they represent a diminutive 



