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ance in the sections of the walls of these organs, as if their parietes 

 were composed, not of a single simple membrane, but of two such 

 membranes with molecules or exceedingly minute vesicles intersper- 

 sed between them. I have carefully examined the cuttings of the 

 wood of the recent Piper nigrum, but have been unable to detect the 

 slightest indication of the existence of similar vesicles in any part of 

 its structure. 



Note. — Having been present at the reading of Dr. A. Farre's paper 

 " On certain phenomena observed in the genus Nitella, as illustrative 

 of the peculiar structure recently discovered by Mr. Bowerbank in a 

 fossil wood from the London clay." I was induced again to examine 

 the cuttings of fossil wood, and I observed that there were, in many 

 cases, the remains of circular granulated masses, which were either 

 attached to or reposing upon the large vesicular bodies, as represented 

 at c, fig. 3 — 5, pi. ii. or sometimes, although rarely, floating freely within 

 the parietes of the vessel, as at d, fig. 4, pi. ii. When examined with 

 a power of 1000 linear their granulated structure is very apparent, and 

 they present a striking resemblance to the granulated masses described 

 by my friend Dr. A. Farre, but they differ in situation, as in the fossil 

 they were always without, while in Nitella they are situated within 

 the vesicular body. Their situation in the fossil vesicles, supposing 

 them to be projecting from the surface but covered by the outer filmy 

 coat of the vesicle, would render them, both in situation and structure, 

 exceedingly similar to the cytoblast and the cell which it developes, 

 as described by Schleiden ; but the same idea will not apply to the 

 granulated masses in the recent plant, unless it be that in this case 

 the aggregation of the globules of circulation is the first step towards 

 the formation of a cytoblast, or of a congeries of those organs : but 

 this is a question of such an occult nature, that I but humbly presume 

 to suggest these ideas in the hope that it may induce others who are 

 much better acquainted with vegetable anatomy and physiology, to 

 endeavour to work out this interesting and difficult problem. 



