206. - The American Naturalist, [March, 
bility,?”"—~. e., variations of Class I. In the analysis of such effects 
effects we should carefully examine: 
(a) Whether this variability in all the characters of the organ- _ 
ism is an éffect of the action of Environment directly upon the 
germ-cells, through the general channels of increased or diminished 
nutrition; or, whether the environment produces a general dis- 
turbance of the functions of the organism, and this acquired dis- 
position to altered functions is transmitted to the germ-cells.* 
(6) Whether changed environment produces variability in any 
special characters or in all characters alike? Here again the 
question as to the mediate action of the somatic cells comes up, 
and is not only much more pertinent than in (a), but probably 
more capable of solution. 
On these points Weismann holds that luxuriance of growth 
results from the better nutrition of the germ-cells during develop- 
ment,” while poverty of growth, or general degeneration, con- 
versely results from deficient nutrition of the germ-cells, as in the 
case of Falkland ponies.” The effects of these influences he 
thinks may be more specialized; they may act only upon certain 
parts of the germ-plasma.** Weismann discusses such cases as. 
follows (p. 433). Observe that the modifications referred to are 
not necessarily adaptive: 
“The wild pansy does not change at once when planted in gar- 
den soil ; at first it remains apparently unchanged, but sooner or 
later in the course of generations, variations, chiefly in the color 
and size of the flowers, begin to appear; these are propagated by 
31 This we can attribute to the greater molecular activity of the cells. Darwin believed 
(a) that says to new conditions must be long continued to set up any new variation. 
(6) Excess of food increases variability. (c) Chan conditions may affect the whole 
organism, or saath parts alone, or merely the reproductive system. (d) Indefinite varia- 
bility is the commonest result of changed conditions. 
38 The point raised by Mivart (Nature, Nov, — 1889, p. sep is not fairly taken. Of 
course nutrition must pass through some somatic cells of th digestive system on its 
way to the germ-oelis; this is a different matter from its first passing to to the peripheral 
e 
‘ 
haoi 1 > rae aA 
3 Biol. Mem.,p. 98. 
> Op. cit., p. 99. 
4. 
Op. cit., p. 104. Oras discussed upon p. 408, in the criticism of Hoffman's experi- 
ments upon flowers, 
