MM. Bornet and Thuret on the Fecundation of the Floridese. 37 



organs. Thus, in Ceramium decurrens, Harv., we have most 

 distinctly seen the corpuscles soldered to the tube of the tricho- 

 gyne. Various species of Polysiphonia have likewise presented 

 us with frequent and perfectly decisive examples of this. In 

 these plants the corpuscles are often seen implanted upon the 

 trichogyne by a small process, which is very short, but perfectly 

 visible ; and when the functions of the trichogyne are accom- 

 plished, we still, for some time, find it bearing the empty cor- 

 puscles suspended from its apex. We may instance especially 

 Chondria tenuissima, Ag., as one of the Algse in which the copu- 

 lation of the two organs may be ascertained the more distinctly 

 because both of them are of a size which is not usual in the 

 rioridese. The antheridial corpuscles are, moreover, remarkable 

 for their elongate form. The trichogyne is inflated into a club 

 at its apex ; and as it is twice as large as that of the Polysiphonia^ 

 it is easy to study its structure. The membrane of which the 

 walls are formed, which is very visible on the sides of the tube, 

 is so attenuated at the apex that it eludes the eye, and the re- 

 fringent protoplasm with which the trichogyne is filled appears 

 to be destitute of an envelope at this point. When one of the 

 corpuscles comes into contact with this part, it unites therewith 

 by a portion of its surface, and very soon no line of demarcation 

 between the two organs can be distinguished ; the finely granular 

 matter which they contain mingles ; frequently the apex of the 

 trichogyne swells and becomes deformed, in consequence of the 

 partial fusion which takes place between them ; its contents be- 

 come detached from the walls of the tube, and contract, and 

 then we no longer see anything in the trichogyne but a row of 

 a few irregular granules to the apex of which the remains of one 

 or several corpuscles are still attached. 



The number of corpuscles emitted by the antheridia is very 

 considerable, and they are often found scattered among the hairs 

 with which nearly all the Floridese are provided. This abun- 

 dance explains how fecundation may be accomplished in these 

 plants, notwithstanding the obstacles which seem to be opposed 

 to it by the dioeciousness of most of them, the immobility of the 

 fecundating corpuscles, and the fugacity of the trichogyne. We 

 may add, moreover, that on examining the cystocarps borne by 

 a specimen in a good state of fructification, we may observe a 

 certain numberof them the development of which has not passed 

 the period at which they were furnished with a trichogyne : these 

 have become simple organs of vegetation ; but their origin is 

 recognized from their form and the position which they occupy 

 on the frond. It seems natural to attribute the frequency of these 

 abortions to the circumstance that the contact of the corpuscles 

 with the trichogyne has not been effected at the proper time. 



From the preceding observations it follows that the phenomena 



