VI. 



Recent Researches on Olive-Brown Seaweeds. 



ALTHOUGH the nature and functions of the contents of the 

 conceptacles of the Fucaceas were well-known previously, there 

 was no definite account of the development of these bodies them- 

 selves until 1880, when the first thorough examination of the subject 

 was made by Professor Bower (i). He gives the views of earlier 

 writers, and tells us that Reinke looked on the bodies variously 

 called Fasergriibchen, cryptostomata, vegetative and neutral concep- 

 tacles (simply conceptacles full of hairs but without antheridia or 

 oogonia) as the " type of these structures " originating " by a separa- 

 tion of four or five neighbouring cells of the limiting tissue from one 

 another. He compares this process with the formation of the resin- 

 passages in the Coniferse." 



It is interesting to see that Luerssen published four years later a 

 different view, and one nearer the truth, though he does not describe 

 the development of the conceptacle in any detail. 



Professor Bower next made an investigation of the subject, and 

 described the whole development of the Fucaceous conceptacle in all 

 its detail. He showed that " the division of the outer cell of the 

 limiting tissue of the thallus by vertical walls into four, ceases 

 in certain cases. The division by walls parallel to the surface, 

 however, continues. A linear series of cells is thus formed which 

 may be traced some distance into the tissues, but which is terminated 

 by a single cell only. Later, the activity of division in the horizontal 

 direction also ceases, and as the terminal cell of the series does 

 not increase in size, the result is that it is surpassed by the tissues 

 surrounding it. The terminal cell of this series we may call the 

 ^ initial ' cell of the conceptacle, the cell immediately beneath it may 

 be termed the ' basal ' cell." 



The development of both cryptostoma and conceptacle is shown 

 by Professor Bower to be the same, and this fact has, of course, given 

 rise to theories as to which was the earlier of the two in the history 

 of the Fucaceae. Professor Bower takes the view that the crypto- 

 stoma is an abortive conceptacle, and proposes the term " neutral '" 

 or "sterile" conceptacle. Oltmanns (2), on the other liand, takes the 

 view that the cryptostomata are the older of the two, and have in 

 course of time come to bear oogonia and antheridia ; while I (3) 



