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~ 
88 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
trations at which bursting occurs, the protoplasm oozes out of 
the broken pollen tube in strings, in such a manner as to show that 
it has a much higher viscosity than has the protoplasm exposed 
to the same reagent at lower concentrations but which neverthe- 
less cause bursting. 
It will thus be seen that the maximum swelling of the proto- 
plasm is at the concentration of the reagent which causes the most 
rapid bursting, and this is higher than the concentration which 
causes swelling which can be utilized in growth. The former is 
chiefly a physical result, the latter physiological. A glance more 
particularly at the behavior of pollen protoplasts toward malic 
acid may be taken, this serving as a typical example. 
At concentration There occurs 
ЖУ {4002 ce. Coagulation and complete syneresis in the course of an hour of all 
the pollen grains (100 per cent.). 
Nj8090....;; The same but more slowly and less completely (95 per cent.). 
Жітбофуг 50 рег cent. of the pollen grain shrinks іп the course of 3 hours, the 
remainder having burst; the protoplasm highly viscous, bursting 
it) 
in strings after some growth (0.3 unit 
N[3200......Bursting of 90 per cent. after 1—т. 5 units growth attained; viscosity 
of protoplasm lower than above but still showing coagulation 
(“clots”). 
N/6400...... 3-5 units growth in 5 hours. Some bursting but no coagulation. 
22 hours later: alive, no further growth. 
Ма Бов ага 8 units growth in 5 hours, no bursting; 22 hours: 16 units growth, 
alive. 
A125,600. сы 4 units growth in 5 hours; 22 hours: 5 units growth, alive. 
Control:...... 4-5 units growth in 5 hours; 22 hours: 5 units growth, alive. 
In formic acid, bursting unaccompanied by coagulation oc- 
curred in N/25,600 (with 20 per cent cane sugar) after one unit of 
growth was attained. Partial coagulation occurred in N/6400, 
more in N/3200 and complete in N/1600. 
The above results indicate that the protoplasm of pollen grains 
is affected by acids and alkalis in the same fashion as geiatin, and 
that the increased swelling caused by such reagents can actually 
be used in growth. "The extreme sensitiveness of this protoplasm 
to low concentrations of acids and alkalis, as evidenced in coagu- 
lation and syneresis in the higher, and in the swelling and growth 
in the lower, is to be noted. It has become patent that the mech- 
anism of growth in more complex plants includes emulsoids which 
exhibit swellings at much higher concentrations of acids and 
