325 



" Some part of the law, I believe, is made tolerably clear, viz., that fibre is com- 

 posed of granules arranging themselves lite beads on a string, which become nourish- 

 ed by the contents of the vessel until a perfect thread is the result, and the direction 

 this takes seems to me to be the result of some special power residing in the vessel 

 under the control of the whole plant, probably electrical ; and which is modified in the 

 several vessels I have enumerated : farther than this I believe we cannot go, though 

 nature occasionally alters forms, she seldom varies much in her laws, but what these 

 may be it is forbidden the eye of man at present to detect, and they appear to me, 

 though operating in such minute spaces, to be stamped with as much permanency of 

 power in the formation of these curious and elegant organs, as those laws on a grander 

 scale are in the fashioning of our owii frame, or in the maintaining of the stability of 

 the universe." — p. 11. 



IV. — On certain Phenomena observed in the genus Nitella, as illustrative of 

 the peculiar structure recently discovered by Mr. Boiverbank, in a Fos- 

 sil Wood from the London Clay. By Arthur Farre, M.D., F.R.S., 

 &c. 



Dr. Farre's paper on Nitella is highly interesting, as illustrative, in 

 some degree, of appearances previously detected in fossil wood by Mr. 

 Bowerbank. The author had procured some specimens of Nitella 

 flexilis for the purpose of observing the circulation of the sap : up to 

 the 4th of April this was going on vigorously, but two days afterwards 

 it had entirely ceased, and certain green particles, previously lining 

 the interior of the stem, had shrunk from the parietes, and, together 

 with the green circulatory matter, was collected in iiTegular masses 

 within the tube. Five days afterwards Dr. Farre found that in many 

 of the joints these irregular masses had resolved themselves into glo- 

 bular bodies of a brown colour, the tubes being left as transparent as 

 glass, and the brown globules appearing as an irregular row of beads 

 in the interior. In almost all the globules was a cup-shaped depres- 

 sion, generally so situated as to face the surface of the tube in the cen- 

 tre of the depression : a small collection of brown gi'anules, of about 

 uniform size with the globules of circulation, was always present. 

 The brown bodies, on being torn open, were found to consist of a 

 very thin investing capsule, filled with the green granules of the plant 

 mixed with mucous fluid. 



" It appears then that this remarkable change had taken place within a week after 

 the circulation had been observed to be going on vigorously in the plant. And the 

 nature of the change appears to be this. The green granules which line the internal 

 surface of the living joints desert the parietes, and, together with the green circulating 

 granules of the interior collect together in irregular masses in the centre of the tube, 

 which then resolve themselves into irregular spheres, still retaining the granular out- 

 line indicative of their formation by aggregation, but which they afterwards lose on 



