Igl6 ] ROE—COXCEPTACLE IN FUCUS 239 



Simons in 1906, in a study of Sargassum (27), claims a develop- 

 ment of conceptacle "At variance with all the prominent character- 

 istics .... of the conceptacle as described by Bower." The 

 initial does not break down, but is an active cell producing the 

 entire conceptacle. Adjacent cortical tissue is in no way involved 

 in the process (p. 1 69) . " Both the conceptacles and cryptostomata 

 originate in a single flask-shaped initial which develops the entire 

 structure. The first division of the initial results in two unlike 

 segments: a large lower cell which develops the walls of the con- 

 ceptacle and cryptostoma; and an upper cell, the tongue cell, 

 which either remains inactive, divides to form a short filament, or 

 degenerates. The "initial" cell of Bower is apparently the 

 tongue cell, a product of the true initial cell. The conceptacle 

 and cryptostoma are undoubtedly homologous structures. Every 

 stage of development in both structures is the same, from the 

 appearance of the similar initial cells to the development of para- 

 physes in the cryptostomata and sexual organs in the conceptacle" 



(p. 179). 



Summary of literature 



The various theories described in the foregoing seem to resolve 

 themselves into three categories: (1) the conceptacle or hairpit 

 is a slight modification of the external layer of the thallus; this 

 theory was held by Kutzing, Sachs, and Luerssen (15); (2) the 

 conceptacle is a product of one or more initials, which do or do not 

 disintegrate; their basal segments form the basal portion, whereas 

 adjacent cortical tissue completes the sides of the structure; this 

 theory was held by Reinke, Bower, Valiante, Oltmanns, 

 Barton, Mitchell, Whitting, Murray, Holtz, Falkenburg 

 (7), and others; (3) the conceptacle is a product of a single initial 

 whose segments develop the entire body; this is the theory of 

 Simons. All of these workers agree, more or less, that conceptacles 

 and hairpits are homologous structures. 



Description 



In a study of three species of Focus and of Splachnidium rugosum 

 and a rather superficial examination of Sargassum filipendtda and 

 Hormosira. the writer found evidence which supports the early 



