34 MINNESOTA BOTANICAL STUDIES. 



The walls of these cells stain more deeply than those of normal 

 cells, the nuclei disappear and the chromatophores fuse together 

 into a dark mass. The affected cells collapse gradually, be- 

 ginning at the outer end. Often a little conical remnant of the 

 shrunken cell may be seen on its basal cell. The walls and 

 contents of the disintegrating cells change into a mucilaginous 

 substance. 



Thus far my observations agree with those made by F. O. 

 Bower. 1 Bower states that the epidermal cell collapses, but 

 that the basal cell persists, and that it sinks farther and farther 

 into the cavity of the conceptacle, and that the lateral daughter 

 cells of the central basal cell by their division form the lining 

 wall of the cavity. He seeks to limit the disintegration of the 

 epidermis at first to one cell and to make its basal cell the cen- 

 ter of the whole process of the development of the conceptacle. 



The serial sections made by me for the investigation of this 

 matter do not show that the disintegration is thus confined to 

 one single epidermal cell. Occasionally several will be equally 

 far advanced in decay. Naturally one or the other of these 

 may decay more quickly than the rest, producing thus a line of 

 weakness and apparently a central axis about which the other 

 decaying cells are grouped. 



Again, it was not found that the basal cell or cells of the dis- 

 integrating epidermal cells persisted. On the contrary, they 

 and several rows of cells below, perhaps five or six, share in 

 this disintegration. It was frequently possible to make out the 

 remains of the disintegrating cells in the mucilaginous mass to 

 which they changed, and with which the cavity formed by their 

 collapse was filled. 



Neither did it appear that the basal cutoffs of the epidermal 

 cells produced lateral daughter cells to line the cavity. It did 

 appear that they divided chiefly periclinally and somewhat 

 radially, forming five or six rows of meristematic cells, the outer 

 rows disintegrating and forming the cavity ; the deeper ones 

 persisting and finally forming the inner wall of the conceptacle 

 and giving rise to paraphases and the reproductive organs. 

 Bower shows figures like /p, PL XI., in which the two cells, 

 b and c on either side of the central basal cell a, might suggest 

 that they were the lateral daughter cells of this basal cell. But 



'Bower. Development of the Conceptacle in Fucacese. Qr. Jr. Mic. Sci. 36 . 



1880. 



