of the Endosperm during Germination. 451 



Examination of the cell walls about the region where this 

 change is in progress shews that the action of the ferment on the 

 walls does not proceed in a centrifugal manner, as was seen to 

 be the case in Tamus ; for instead of the ferment originating in 

 the embryo and proceeding outwards to the endosperm, it appears 

 to originate in the endosperm and proceed inwards towards the 

 embryo, and so work in a centripetal manner. This method of 

 attack, which can easily be followed with the help of suitable 

 reagents, such as Congo red or picric aniline blue, gives a 

 very peculiar and characteristic appearance to sections of the 

 endosperm of germinating seeds (Fig. 13), for the walls which are 

 attacked shew stained mucilaginous areas on their sides towards 

 the periphery, i.e. away from the centre of the seed, whilst the 

 sides towards the centre retain their sharp contours and shew little 

 sign of disorganisation (Figs. 14 and 15). 



The relation between the progress of the ferment action and 

 distribution of the " connecting threads " is not always very clear, 

 for though in some cases a boring out along certain of the threads 

 can be observed, yet in many others the dissolution of the walls 

 appears to take place without any obvious connection between them. 



Cell walls on which the ferment has just commenced its attack 

 frequently shew a jagged edge, owing to the ferment forming little 

 V-shaped disorganized areas, which are at first separated from each 

 other by thin slips of the unaltered cell wall (Fig. 14), and in such 

 cases the action appears to take place along the canals of certain 

 of the connecting threads, but when the disorganization is more 

 advanced the mucilaginous portions of the wall are usually found 

 to be bounded by rounded surfaces of the unaltered cell wall, and 

 it is then difficult to make out that the ferment action proceeds by 

 means of the threads (Fig. 15). The disorganization of the wall 

 gradually extends until only a few islands of cells situated in 

 a mucilaginous matrix remain, shewing the original composition of 

 the wall, and these finally disappear, leaving an uniform wall of 

 hydrated cellulose in which groups of connecting threads can still 

 be clearly seen (Fig. 14). 



When germination has proceeded for some time sections of the 

 endosperm shew that the centripetal action of the ferment has 

 commenced in cell walls at some considerable distance from the 

 embryonic cleft, especially in cells under the testa (Figs. 13 and 14). 

 The progress of the ferment in these distant walls is essentially the 

 same as that just described, and sections treated with methylene 

 blue shew that there is a very large unstained area around the 

 embryonic cleft. With the vigorous growth of the embryo the 

 cotyledons increase in size and continue to encroach upon the 

 endosperm until the reserve materials stored in the cells and cell 

 walls are completely absorbed, and, as soon as this has been 



VOL. XL PT. VI. 32 



