RAMENTA. 



445 



To-day I commenced examining Adiantum, with the view of deter- 

 mining if possible the nature of its reproductive organs, and the mode 

 in which they are impregnated, if they are impregnated at all. 



As I had long been aware that the fructification of each frond is 

 a thing to be determined at a very early period, and that if not 

 determined then, it is never likely to be determined afterwards, my 

 attention was directed more strongly, if possible, than it would have 

 been otherwise, to examining the subject at the earliest possible stage 

 of its development. 



The first piece examined gave me the idea that I had trouve 

 le nceud de 1' affaire ; the second made me doubt this ; the subsequent 

 ones went far to disprove it. 



I was immediately struck with the resemblance of those organs, 

 called ramenta, to what are fairly assumed to be the male bodies, 

 in certain other families of the same grand division ; and I at once 

 came to the conclusion, that the barren fronds, were barren, because 

 almost destitute of these ramenta ; and that as these ramenta were 

 confined to the base of the stalk, that is, to the part below its first 

 ramification, an obvious necessity existed for the peculiar nature of 

 the vernation. 



Further examination of the thing, especially of the base of the 

 stipes and the adjoining part of the rhizoma, threw me back almost 

 into my original difficulties. I find that the rhizoma is entirely 

 covered with ramenta, which are brown, much detached at the base, 

 and obviously represent a low form of leaf, i. e. in appearance, per- 

 haps partly in function, but not in structure. Among these, mature 

 ramenta at the punctas of prolongation, which appear to be very 

 irregular, are concealed, others much smaller, and much narrower, 

 (which bear as obvious a resemblance, or even more so to the male 

 organs of certain other orders,) than the ramenta on the stipes. 

 These are never entirely brown, the end cell alone is coloured, but 

 though occasionally tinged with brown, they are filled with some 

 fluid (even this is not so at first,) but do not appear to open. I 

 believe that subsequently all become highly tinged with brown, but 

 what increase of growth they subsequently undergo, I know not. 

 The terminal cell is always solitary, very often attached to the one 

 next it, which is generally single, obliquely placed, occasionally 

 looking like the dimidiate calyptra capping a young seta. The 

 number of cells forming the base, or dilated part varies, but is al- 

 ways small in proportion to the larger ramenta, or protecting scales : 



