106 Mr. W. Gardiner. The Histology of the Cell Wall 



and the phenomena which accompany germination were investi- 

 gated in the endosperm of Tamus communis only. The threads are 

 round to be present at a very early stage, and can be detected even in 

 the very youngest and thinnest walls. They are at first uniformly 

 distributed over the cell membrane. In the case of the side walls, as 

 surface growth proceeds, small groups of threads become separated 

 from one another by intervening areas of clear membrane, while in 

 ihe end walls, where the extension of surface is less, this segregation 

 into groups does not take place. In the early stages the growth in 

 thickness of the wall is not uniform, and pits are formed on the side 

 walls at those points where thread groups occur; but they have only 

 a transient existence, and ultimately disappear. It is, however, 

 interesting to note that the vegetative tissue of Tamus communis 

 consists for the most part of pitted cells. 



In. germination the ferment, in the first instance, appears to be 

 conducted into the wall by means of certain of the threads, but 

 when once an entrance is effected the corrosive action rapidly 

 spreads quite independently of the threads, becoming the more 

 potent as it reaches the neighbourhood of mucilaginous and less 

 resistent middle lamella. In a given wall the penetration commences 

 simultaneously at several centres, and at each centre the affected areas 

 assume the general form of small cones with their apices directed 

 towards the cell lumen (fig. 3). Moreover, since the action of the 



Tig. 3. 



ferment soon extends from cell to cell in two adjoining cells, where 

 the common wall is affected on both sides, each side having its cone, 

 the base of one cone appears opposed to that of the other. At this 

 stage, by appropriate staining, the threads may still be seen shining 

 through tbe disorganised mucilage of the affected areas. As the 

 ferment action proceeds the boundaries of the several areas con- 

 tinually extend and at length unite when the whole of the wall is 

 involved. The disorganisation of the wall is accompanied by 

 marked stratification. The sphere of influence of the ferment action 



