14 Brannon. — The Structure and Development of 



Presently these small spherical bodies separate from their 

 mother-cells and pass into the gelatinous layer which covers 

 the patches of antheridia. 



These antherozoids are non-motile, consequently depending 

 upon water-currents for distribution so as to come into contact 

 with trichogynes. Repeated tests for their nuclei gave 

 negative results, though the granular contents show deeply- 

 stained fragmentary particles. 



Because the male plants are smaller and apparently much 

 more rare than the female, and produce non-ciliated anthero- 

 zoids, it is obvious that the male plants must generate an 

 extraordinarily large number of them. This demand is 

 abundantly supplied by the myriads of antherozoids developed 

 in the apical manner described above. 



Development of the Cystocarp. 



The method of the development of the cystocarps, which 

 are promiscuously distributed on either side of the female 

 frond of Grinnellia, appears more difficult to harmonize with 

 the theory of Schmitz than does the manner of formation of the 

 frond and the antheridia. The study of the initial develop- 

 ment of the cystocarp, however, not only shows that it 

 conforms to his theory of the development of most of the 

 Florideae, but further testifies that the whole tissue of this 

 leaf-like Alga is developed by apical growth of ramifying 

 threads. In the apical and marginal regions of partially 

 mature female plants, and distributed promiscuously over the 

 entire surface of young female fronds, are isolated individual 

 cells assuming a triangular shape (Fig. lo). They are 

 directed apically outward and upward in such a manner 

 that if a line were drawn through the long axis of any one of 

 them to the median plane of the frond, an angle of 50° to 75° 

 with the midrib would be formed. These are centres of 

 active growth, and develop groups of cells (Fig. 1 1 and Fig. 1 2) 

 similar in appearance and outline to those at the apices of 

 the growing plants. After twenty to thirty cells have been 



