ANATOMY AND PHYSIOLOGY OF 



a layer of considerable thickness, and in wliicli no cellular tias yet been 

 shewn to exist. 



E. CONTENTS OF CELLS. 



In the present state of our knowledge it is an impossibility to 

 give even a tolerably complete description of the contents of eells, 

 since of the large number of organic compounds produced by the 

 vegetative processes, almost all of which occur in the cells, only a 

 very small number can be demonstrated at present in the plant 

 itself by means of the microscope, since most of them occur in 

 solution in the cell-sap and in too small quantity for them to be 

 rendered visible by re-agents. I must, therefore, confine myself to 

 the mention of the organized productions found in cells, and the 

 universally diffused substances. 



a. Frimordial Utricle, Protoplasm and Wucleus, 



In all young cells, whatever their subsequent contents may be, 

 whether they persist in the stage of cells or become changed into 

 vascular utricles, a series of formations are met with, which dis- 

 appear again more or less perfectly in the subsequent periods of 

 life, and which stand in the closest relation to the origin and 

 growth of the young cell, but only in particular cases in relation 

 to their later functions. 



If a tissue composed of young cells be left some time in alcohol, 

 or treated with nitiic or muriatic acid, a very thin, finely granular 

 membrane becomes detached from the inside of the wall of the 

 cells, in the form of a closed vesicle, which becomes more or less 

 contracted, and consequently removes all the contents of the 

 cell, which are enclosed in this vesicle, from the wall of the cell. 

 Reasons hereafter to be discussed have led me to call this inner 



cell (fig. 43, a) the primordial 

 ^'^^' ^^' utrideipQ^imordialschlauch) 



(H. V. Mohl, " Remarhs on 

 the Structure of the Vege- 

 table Cell/' — Bot Zeitung, 

 1844, 273. Transl. in Tay- 

 lor's Scientific Memoirs, vol. 

 iv. p. 91). Iodine colours it 

 yellow, and it is therefore 

 probably always nitrogen- 

 ous. According to Mulder, 

 proteine may be detected in 

 it in many, but not all, cases, 

 by nitric acid. Cellulose 

 cannot be found in it, and 

 a, the the compound of which it is 

 composed is as yet unknown. 

 The primordial utricle disappears again with the thickening of 



Cell of tlio leaf of Jmigermannia TayloH. 

 primordial utricle scpaxated by the action of lodme 



