ipi2] YAMANOUCHI—CUTLERIA 461 



pigment structures 



from 



pigment spot is associated with 



female gamete, and a small red pigment 



upon a small plastid is characteristic of the male gamete. Although 

 the plastid bearing the red pigment of the male gamete grows in 

 size after its introduction into the cytoplasm of the female gamete, 

 yet it seldom becomes equal in size. This difference in size of 

 the two pigment spots is maintained as far as the present 

 observation goes. Fig. 9 represents some of the stages in the 

 development of sporelings from the 1 -celled to the 5-celled stage, 

 indicating the various positions of the two red pigments of 

 male and female origin. The red pigment was recognizable 

 even up to the 16-celled stage, and beyond the 20-celled stage 



hard to recognize, probably on account of the disin- 

 tegration of the coloring matters. It seems probable that the 



becomes 



gamete 



with 



As stated before, the sporelings develop continuously in one 

 direction, and as a consequence after about ten days there is pro- 

 duced a columnar structure standing upright upon the substratum, 

 and then the direction of the growth becomes changed. Cells of 

 the basal portion of the columnar sporeling divide laterally, instead 

 of in the direction of the axis of the growth, so that by repeated 

 cell division there is produced a flat expansion, the whole structure 

 of which might be well compared with a candlestick, the candle 

 being the column and the base the newly developed flat expansion. 

 The basal expansion is developed by the repeated periodic cell 

 divisions on the lateral margin, which causes a zonation like that 

 in Peyssonnelia; besides, the thallus is characterized by inter- 

 calary growth. Sporelings at about 20 days after fertilization are 

 shown in fig, 10, a. Later the upright column does not seem to 

 grow much, only the basal expansion continuing to develop. 

 Sporelings 30 days old are shown in fig. 10, b. In 55 days old 

 sporelings, the growth of the column has ceased, and it remains 

 small, hardly recognizable to the naked eye, while the basal expan- 

 sion reaches a considerably larger size and becomes well fitted to 

 flourish as an independent creeping structure (fig. 10, c, d). 



