igi6] ROE—CO.XCEPTACLE IN FUCUS 233 



Sachs in 1875 (26) says (p. 227) of the conceptacle of the 

 Fucaceae: 



"These conceptacles are not formed in the interior of the tissue, but as 

 depressions in the surface which become walled in by the surrounding tissue, 

 and so overgrown that at length only a narrow channel remains, opening out- 

 ward. The layer of cells which clothes the hollow is thus a continuation of the 

 external epidermal layer of the thallus, and since the filaments which produce 

 the antheridia and oogonia sprout from these, these latter are, morphologically, 

 trichomes." 



In the same year Reixke (21) published an account of Fucus 

 ■aesiculosus, followed a year later by a much more inclusive record 

 of investigations (22) of a large number of closely related genera. 

 In each paper he discusses the origin and development of both 

 hairpits (" Fasergriibchen " ) and conceptacles. On p. 337 he gives 

 the details. The first indication of a pit is noticed on the lip 

 close to the growing point, where a few neighboring epidermal cells 

 separate themselves from other tissue (comparable to formation 

 of resin ducts in conifers) and form between them an intercellular 

 space rilled with mucilaginous substance. Also the cortical cells, 

 just beneath, are involved in this separation, and the cavity thus 

 developed widens into flask-form, wherein the original meriste- 

 matic cells take on the usual character of the border cells. These 

 border cells develop first into papillae, and by subsequent division 

 into hairs which project beyond the mouth of the pit. 



The conceptacle is regarded by Reinke as a structure compar- 

 able to the flower of angiosperms, and is a metamorphosed thallus 

 apex and branches. In this metamorphosis hairpits are changed 

 into conceptacles (p. 338). The details of development are about 

 as in the hairpit (p. 339). On the exterior the cavity is rendered 

 firm by the epidermis and a few layers of cortical tissue. The 

 epidermis stops short at each side of the ostiole; the walls are 

 formed by small, nearly isodiametric cells corresponding to the 

 cortex. Hairs spring from the base of the cavity and project 

 beyond the ostiole. Because of the place of origin (close to the 

 growing point) and similarity in method of development (separa- 

 tion of groups of cells from adjacent external cells, etc.), he con- 

 siders the conceptacle the homologue of the hairpit (p. 340), and 



