Grinnellia americana, Harv. 21 



gives additional testimony to the belief that the sterile 

 filaments connecting pericarp and cortical cells in the base of 

 the cystocarp (Fig. 31) are agents for conducting food-material 

 from the pericarp to the egg-cells of the cystocarp. 



In Mr. T. Johnson's work on Sphaerococcus and Gracilaria, 

 he figures and describes a complicated fusion of the procarpic 

 cells shortly after fertilization of the trichogyne. A very 

 large cell is the result of this fusion of several cells and from 

 this the ooblastema-filaments develop. Nothing of this nature 

 is discovered in the growth of the cystocarp of Grinnellia. 

 It seems, on the contrary, that the large protoplasmic 

 companion-cells simply contribute nourishment to the large 

 central cell through the pits in the walls of their connecting 

 processes (Fig. 26/), and that this large cell gives rise to a few 

 ooblastema-filaments and to a papilla-like growth of cells 

 containing dense protoplasmic contents from which nearly all 

 the ooblastema-filaments develop (Figs. 24, 25). In this 

 way the production of these filaments is continued at different 

 intervals and gives rise to chains of carpospores of various 

 ages, ranging from mature to very young forms (Figs. 22, 26). 



The lack of fusion in the auxiliary cells of Grinnellia is one 

 of the most notable points observed in the study of its 

 development. It is especially peculiar, as fusion of basal, 

 procarpic cells has been reported in the related genus 

 Gracilaria. A careful examination of a very large number of 

 stained and unstained preparations of median longitudinal 

 and transverse sections of young and old cystocarps failed to 

 reveal a single case of cell-fusion. The cell-walls of the old, 

 empty, auxiliary cells in the base of the mature cystocarps 

 were unabsorbed, though often irregular and distorted, because 

 the cell-contents had been used in supplying food-material to 

 the ooblastema-filaments and carpospores. As only a thin 

 membrane is left to mark the cell-walls of the empty auxiliary 

 cells, the freezing method was especially valuable in exactly 

 determining whether there had been any true fusion of 

 adjacent cells. Any process employed in preparation for 

 sectioning, which would have produced even a slight rupture 



