144 



loc. cit., Fig. 109) is in the lower cell and divides it into two 

 cells, which are of unequal size (Figs. 5 and 6). The larger of 

 these may divide further into two nearly equal cells by a 

 vertical wall (Fig. 6) but no further divisions could be found 

 in the species. 



Figure 8 gives two views of a young prothallium of four 

 cells showing their arrangement. 



In 0. pedunculosum, which may perhaps be identical with 

 some of our forms, Mettenius found that the older prothallia 

 may develop chlorophyll under certain conditions, and a special 

 effort was made to determine whether there was any chloro- 

 phyll found in the earlier stages of germination of 0. moluc- 

 canum. It was found that while in the ungerminated spore and 

 during the first stages of development no chlorophyll could be 

 detected, not infrequently a small amount ef chlorophyll was 

 formed in the three or four-celled prothallia. Not uncommonly 

 specimens were encountered in which there were one to three 

 distinct chromatophores of a pale, but unmistakable, green 

 color (Fig. 4). In one instance a number of specimens which 

 had been kept on a slide in a moist chamber for several days 

 showed chromatophores of a golden brown color, but the cause 

 of this could not be determined. The amount of chlorophyll 

 is evidently insufficient for the independent growth of the 

 young gametojihyte, and after a few weeks or a month, 

 the granular contents have almost disappeared and many of 

 the young prothallia have the cells collapsed and are evi- 

 dently dead. 



In many of the cultures which were kept very wet a 

 Chytridium or some allied fungus attacked them and quickly 

 destroyed them. In another culture, a filamentous fungus was 

 seen, and at first was thought to be possibly the mycorhiza 

 which associates itself with the older prothallia. This fungus, 

 however, grew rapidly and soon destroyed the young prothallia, 

 which in no cases observed in this species, advanced beyond 

 the four-celled stage. 



