PHYSIOLOGICAL BOTANY. 233 



absence of nitrogen in the membrane of the cells of plants, 

 and also upon the presence of nitrogen in the animal 

 kingdom. But supposing that nitrogen were to occur in 

 the membrane of several vegetable cells, would the plants 

 for this reason, cease to be plants? Boussingault has 

 shown that a large quantity of nitrogen exists in plants, 

 but where, has not been positively determined. It is 

 reversing the proper method to commence with chemistry 

 in the study of natural history : and this, first, because 

 chemical analysis is the most difficult ; secondly, because 

 its resources are inexhaustible, and cannot be regarded 

 in the same light as the latter ; and lastly, because it 

 affords us no insight into the intimate structure of organic 

 bodies, as is proved by isomeric substances. The mem- 

 brane of plants is isomeric with starch, as Pay en has 

 shown, and yet the two are very different from each 

 other. 



Investigations upon the Growth of Cells. By Dr. 

 SCHAFFNER of Herstein. Flora, 1845, 451. "If we may 

 be allowed/' says the author, " to deduce conclusions 

 from the investigations which have been detailed, the fol- 

 lowing cells increase by primary cell-formation. 1. The 

 cambium cells (which are subsequently developed into 

 prosenchyma and vascular cells). 2. The cells of the 

 liber, which do not differ materially in their earliest stage 

 from those of the cambium, but form a distinct system. 

 3. Part of the cells of the parenchyma, to which the cells 

 of the leaf (excepting those of the cotyledons), and the 

 cells of the parenchyma of the fruit of the apple and the 

 plum provisionally belong, i. e. should the absence of 

 secondary cells in them be confirmed." This is of no im- 

 portance, the point is whether the so-called secondary cells 

 are really such, i. e. are formed from the parent-cell. " By 

 the formation of secondary cells, the remaining cells of the 

 parenchyma increase, as seen, e. g. in the cells of the pith 

 and of the bark, &c." (???) " Increase of cells by division 

 certainly does not occur in Phanerogamous plants." (?) 





