PSILOTUM. 



497 



quently contained in a membrane, within which, even 

 the peculiar aggregation of the granular matter by 

 which the spores are first traced out may be seen. 



With these compound cells or bags are mixed origin- 

 al cells, as is evident from their appearance which is 

 peculiar, being grumous with a marked nucleus, some- 

 times with an evident hyaline membrane, always after 

 acid or iodine. I have seen also decided appearances in 

 these original cells while in groups, affecting the whole 

 group or part of it, which exactly put on the look of 

 the globular cells subsequently contained in the bags, 

 viz. an incrusted appearance, manifest enlargement, hya- 

 line disc, and a nucleus scarcely observable except after 

 acid. 



But then in what manner do these, (which from their 

 abundance may be supposed to be metamorphosed from 

 nearly the whole original tissue,) become enclosed in 

 bags ? Can the grume around each mass become mem- 

 brane. ? 



There can be no doubt moreover, that the original 

 cells, i. e. the grumous nucleary ones, become less and less 

 frequent as the developement proceeds, although some 

 remain at least in the segragated state to a late period. 



When the bags are seen, there seems to be consider- 

 able variety in the size and number of the enclosed 

 cells, but as the time for the marking out of the sporula 

 approaches, they become uniform. 



Of the parietal cells I know nothing. Some of the ge- 

 neral circumstances agree with Isoetes, such as the first 

 stage where the tissue of each cell in the centre is trans- 

 parent, lax and large the extension of this outwards, the 

 returned uniformity of appearance, the compound cells, 

 becoming subsequently divided into as many component 

 parts as nuclei, and the enlargement of some part of 

 these, or the whole. 



The enclosure of these enlarged incrusted cells in 

 bags, appear to me anomalous. 



3 Q 



