558 General Notes. [July, 
their reaching a certain thickness by apposition growth), the trans- 
formation of less watery to more watery substance will be per- 
formed; in other words, the nucleus and the less dense layers will 
appear. That the inner parts of the grains, taken as a whole, are 
less watery than the peripheral ones, is due also to their being 
extended by the latter. 
The unequal growth of starch-grains in different directions was 
shown in a former paper! to be due to the unequal conveyance of 
material. Starch-grains which are formed in the inner parts of 
chlorophyll or starch-forming granules, and remain surrounded 
y them, have central nuclei. They become eccentric when they 
are formed at the periphery of chlorophyll or starch-forming 
granules, and show constantly the greatest growth where they are 
in contact with them. ; 
The formation of compound grains was also described in the 
paper already quoted, and shown to be due to the growing to- 
gether of free granules, and not, as Nageli holds, to the division 
of simple grains. The development of half compound grains was 
investigated principally in the rhizome of Canna and found to be 
analogous. The structure of grains having their nuclei distant 
from each other, which led Nageli to suppose an intense growing 
of the grains between them, is caused by their being formed at 
distant spots upon the periphery of the chlorophyll, or starch- 
orming granules. e differences in the density of simple grains 
and the partial grains of the half compound and compound ones, 
is due to the extension of the inner by the outer parts. : 
Nageli, and after him most biologists, hold that starch-grains 
agree with protoplasm as to their molecular structure, and are - 
be considered as living bodies. There is no longer any en 
for ascribing to them properties different from those of inert se 
ies ; their cohesion and their optical properties prove conclusively 
that they are sphzrocrystals; they differ from most crystals by 
their property of swelling up in water, but the so-called prote™ 
artificially under the same circumstances in which true ave 
would have been formed2—A. F. W. Schimper, Fohns Hopxim 
University. 
HARDINESS OF THE Eucatyprus,—The paragraph on p. 389 eh 
Naturatist for May, requires qualification ; what Baron Muelle 
no doubt said, was, that in the native places of rowth the blue 
° . *. P 
gum was uninjured sometimes when the thermometer fell to 20 be 
° Fahr. Luminose and hygrometrical conditions in conn 
. Le i J 
1 Botanische Zeitung, 1880. Translated in Quarterly Fournal of Microscopie 
Science, April, 1881. epee 
*These conclusions are based upon the researches of Schmiedeberg (Zeitschryf, 
fiir physiol. Chemie, Vol. 1), Drechsel (Yournal fir praktische Chemie, V 
_ and my own investigations (Zeitschrift fiir Krystallographie, Vol. V)- $ 
