58 PROCEEDINGS OP THE AMERICAN ACADEMY 



scribe a peculiar condition of the frond that was always found in cysto- 

 carpic plants. In the peripheral portion of such a frotid, instead of 

 finding the usual elongated pyriform cells, one sees a large number 

 of small spherical ones arranged in distinct chains (Figs. 14, 17). 

 The transition between the two conditions can be traced without much 

 difficulty, in fronds where the cystocarps have just commenced to 

 develop. It is seen that, when the main part of tlie growth of the 

 plant has taken place, the terminal cells, instead of dividing as fre- 

 quently vertically, divide more frequently transversely, forming short 

 chains of small cells, which afterwards increase considerably in size. 

 Frequently even in the adult fronds the chains of terminal cells are 

 seen to give place to the ones of the usual form at the base of the 

 frond (Fig. 14). There is nothing remarkable in the appearance of 

 the walls or the contents of these chains of cells that would lead one 

 to suppose that they have any special function. The condition of the 

 cells seems merely to be that which is very often seen in the cystocarps 

 of other alg^, where the outer wall of the conceptacle consists of a 

 great number of small cells in chains. In the case of C. Polysipho- 

 nice, the frond is so small in proportion to the cystocarp that the whole 

 of it becomes modified in this change. 



It was not until late in the course of ray examination of C. Poly- 

 siphonice that I discovered the trichogyne and its accompanying 

 organs. The fronds containing them were searched for diligently, but 

 only a few plants were found that were in the right condition. It was 

 undoubtedly too late in the season when I first found the trichogynes 

 to expect them to be common, for then almost all of the cystocarpic 

 fronds were mature. In spite of this, however, sufficient material was 

 found to make out the structure of the undeveloped procarp, and to 

 some extent to follow its development. The trichogyne forms the 

 distal extremity of an irregular chain of cells, which are often con- 

 nected into a more distinct filament than is common with the interior 

 cells of C PoJysij)honice. It represents and is developed out of one of 

 a number of cells, which at first were ordinary terminal cells like the 

 others of the frond. The terminal cells arising from the same basal 

 cell as the developing trichogyne and trichophoric apparatus apparently 

 cease all growth after the latter begin to develop, and soon become 

 buried in the frond. Oiie or more of them often remain, as in Figures 

 18, 19, and 21, c. Tlie remaining cell which is to continue the growth 

 divides, the terminal cell developing into the trichogyne, the lower 

 ones forming the trichophoric apparatus. When fully developed, the 

 trichogyne is very long. The cell itself is about 2-2.5 ft iu diameter, 



