292 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



the starch grains and attributed such a constitution to it. The 

 orange zone which Timberlake found preceding the advent of the 

 cell-plate is very likely composed of carbohydrate which was 

 perhaps in the process of polymerization from a soluble sugar of 

 low molecular weight through the less soluble dextrins, etc. and 

 ultimately into cellulose. The orange-staining bodies in the 

 cytoplasm of so many plant cells may possibly also be carbohy- 

 drate material of varying degrees of polymerization. 



The history of the mother-cell-wall also indicates that during 

 reduction it may be passing through transitional stages leading 

 ultimately to its dissolution and disintegration. In most plant 

 cells the mother-cell-wall persists after mitosis and becomes a 

 part of the cell-wall of each daughter cell. The wall of the pollen- 

 mother-cell, however, like that of other spore-bearing structures 

 disappears as an entity, while the walls of the daughter cells 

 are constructed entirely anew within the mother-cell. As has 

 been shown above, the mother-wall beginning at the time of 

 synapsis continues to thicken to a marked degree during the re- 

 duction divisions, and finally dissolves. It seems hardly possible 

 that this thickening of the mother-cell-wall can be in the nature 

 of growth, such as doubtless does occur in the formation of so 

 permanent a structure as the exine, for example. Chemically 

 considered this thickening of the mother-wall is probably in the 

 nature of a colloidal swelling or hydration. Fischer (19) has 

 recently attempted to demonstrate that hydration is not a stage 

 in the process of solution as it has usually been considered. Though 

 it may be that solution is not an absolutely necessary consequence 

 of hydration, it is still true that very often, if not usually, solution 

 does follow hydration. There is at least this much of a sequence in 

 these cases; and solution involves a greater increase in colloidal dis- 

 persity than does hydration. It, therefore, does not seem illogical 

 to conclude that the thickening of this mother-cell-wall is in the 

 nature of an increase in colloidal dispersity of the substance of the 

 wall, which process continues, and ultimately leads to such extreme 

 dispersity that an entire dissolution of the mother-wall ensues. In 

 addition to the cases of thickening of the mother- wall noted in the 

 table below, Wille figures (81) this condition in 14 dicotyledons. 



