1210 Growth, tts Conditions and Variations. [December, 
centage is highest in the white fleshed varieties. It appears also 
that the per cent of acidity is greater in varieties having dark 
colored flesh. In the pear the percentage called “ sub-acid” is 
decidedly greatest in the white fleshed varieties. This may at 
first seem contradictory to my hypothesis. It should not be for- 
gotten, however, that in the apple and pear a mild acidity greatly 
improves the flavor, and hence this apparent exception is possibly 
the result of selection. 
In the plum no varieties are said to have white flesh. I find, 
however, that in five varieties in which the flesh is called “ amber 
color,” and three called “pale green,” none are called acid; 
while in fifty-nine varieties called “ yellow,” five have some acid, 
in thirty-three called “ greenish yellow,” three are called acid, in 
twenty called “ greenish,” five are called acid, and in nine called 
“greenish yellow,” three are called acid. 
In the other fruits and vegetables I have not found sufficiently 
accurate descriptions to permit me to judge whether the hypoth- 
esis holds or not. : 
If further investigation should discover sufficient evidence in 
this direction to establish a law, this law will have an important 
practical application in the amelioration of fruits and vegetables. 
GROWTH, ITS CONDITIONS AND VARIATIONS. 
BY CHARLES MORRIS. 
(Continued from page 1101, November number.) 
AR back in the history of life we reach a period in which 
crustaceans and mollusks seem to have been the lords of the 
earth. During the greater part of the Palæozoic .age the 
ocean invertebrates were dominant, they grew to great size, devel- 
oped rapidly in functional ability, and swept the seas of ar 
stores of food. We know little of the struggle which then too 
place between the various invertebrate sub-kingdoms, or of their 
probably successive rise to supremacy. Nor can-we trace the 
struggle between the members of each sub-kingdom. So far as 
evidence goes the cephalopods would seem to have been copie 
poraneous in origin with humbler representatives of their G 
and of other races. But this is doubtless an illusion produe 
by an undue crowding together of the geological tablets. g 
This invertebrate era was succeeded by the earliest stage 
