562 , MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Borowikow,^ that the agents which cause swelHng in emulsion 

 colloids would increase growth, and, for the moment, it is not 

 possible to discount his results, which he holds substantiate his 

 assumption. He concerned himself with the period of elongation 

 (Streckungsphase), that period, namely, when the growing cells 

 take on a maximum water volume hy adding to the number and 

 size of vacuoles. And it is this fact which forces the criticism that 

 we have no knowledge at the present moment of how swelling, 

 shrinking, and coagulating reagents affect the relation of changes 

 of hydratation to the capacity of protoplasm to secrete and to 

 hold water within the vacuoles. And when it is pointed out that 

 the water in the vacuoles is not by any means a simple solution of 

 electrolytes, but contains albumin (Loew) and mucilages, and 

 frequently also suspension colloid bodies (tannins, etc.), substances 

 which must act in antagonism to the protoplasm in so far as they 

 will compete with it in the hydratation processes, as also must 

 investing membranes (cellulose and pektose walls, derived muci- 

 lages, such as that of mallows and cacti), we see the need of investi- 

 gation which is directed toward forming some conception of how 

 these interactions proceed. 



The embryo-sac and pollen grain exemplify the above. The 

 former is a group of cells invested by very delicate cellulose 

 membranes, and in which the development of vacuoles reaches a 

 maximum. The resulting mechanism of endosperm-cell and egg- 

 apparatus (in Torenia) is so delicately equilibrated that the whole 

 is thrown out of order by the plasmolytic effects of a solution of 

 the concentration of slightly over o.iN potassium nitrate. It is 

 difficult to conceive the effects of reagents to be identical when 

 operating upon such a system as in the case of the protoplasts of 

 the pollen grain,- from which all water vacuoles (some pollens, such 

 as that of Calla, do not conform to this description) are absent. 

 In this case, the emulsion colloid complex which we call proto- 

 plasm shows at once the changes in hydratation due to reagents. 

 Preliminary studies have shown that the protoplasts can swell 

 after previous shrinkage in concentrated glycerine, salts, sugars, 

 and indeed burst^ at surprisingly high concentrations of these 



' Uebcr die Ursachen des Wachstums der Pflanzen. i. Dot. Inst. Univ. Odessa. 



- Pollen grains of EschschoHzia, Lupinus, and many others are examples. 



'' Pollen of cotton bursts in 50 i)er cent, glycerine, 25 per cent, cane sugar, 0.45N 

 KNO3. That of EschschoHzia freciucnlly hursts in the course of twenty-four hours in 

 very strong glycerine. 



