TRANSACTIONS OF THE SECTIONS. 437 



He regards light as operating upon the green parts of plants 

 in the character of a specific stimulus, calling into action and 

 keeping alive those functions from which the assimilation of 

 cai-bon and the evolution of oxygen result, and that the de- 

 scription of rays which are proportionally more abundant in 

 solar than in artificial light are those most instrumental to the 

 above purposes. 



With regard to the second branch of the inquiry. Professor 

 Daubeny has only proceeded in it so far as to have satisfied 

 himself, that in fine weather a plant consisting chiefly of leaves 

 and stem will, if confined in the same portion of air night and 

 day, and duly supplied with carbonic acid during the sunshine, 

 go on adding to the proportion of oxygen present, so long as 

 it continues healthy, at least up to a certain point, the slight 

 diminution of oxygen and increase of carbonic acid which 

 takes place during the night bearing no considerable pro- 

 portion to the degree in which the contrary effect is observable 

 by day. 



He accounts for the discrepancy between his own results 

 and those reported by Mr. Ellis in his work on Respiration, by 

 his having taken care to remove the plant from the jar imme- 

 diately upon its beginning to suffer from the heat or confine- 

 ment, and from his having carried on the experiments upon a 

 larger and more suitable scale. 



Considering the quantity of oxygen generated by a very 

 small portion of a tree or shrub so introduced, he sees no 

 reason to doubt that the influence of the vegetable may serve 

 as a complete compensation for that of the animal kingdom, 

 especially since this same function appears to belong to every 

 plant which has come under his review, whatever may be its 

 structure or organization. 



On some symmetrical Relations of the Bones of the Mega- 

 therium. By Walter Adam, M.D. 



The author, having examined the bones of the megatherium 

 which are preserved in the Museum of the College of Surgeons, 

 was led to observe their forms according to their symmetrical 

 relations. For this purpose, the coronal breadth of the cra- 

 nium is taken as a common term of reference. It measures 

 8'75 inches, but in the following scale of proportions its breadth 

 is denoted by 10, and all the other measures are altered in the 

 same ratio, and expressed by the nearest integers. Dr. Bar- 

 clay's nomenclature is employed. 



