Considcration of Weismann’s Arguments 185 
alone sufficient to produce in some instances extraor- 
dinarily complicated formations down to the most minute 
peculiarities. The example of Kallima, a well known 
leaf-like butterfly, will at once occur to every one. Never- 
theless it is known that certain Lamarckians have had 
the hardihood to wish to attribute these very perfect 
resemblances to former, voluntary, chromoblastic, mime- 
tic changes which do not now exist in the animal but 
which can be demonstrated even now in certain other 
animals, for instance in some fishes. The absence of 
change in the object taken as a model which was imitated 
only voluntarily at first, has resulted in the gradual with- 
drawal of the imitative color mechanism from the con- 
trol of the animal’s will4® Here it is sufficient to 
remark that the last word has certainly not yet been said 
upon this voluntary mimicry which rightly excites the 
greatest interest. In any case such imitative formations 
as that of Kallima cannot be disposed of by simply refer- 
ring them to natural selection alone, seeing that their 
protective utility can commence to be manifested only 
after they have attained an advanced degree of perfection. 
“A muscle,” insists Weismann, “can become greater 
by use, but a claw, a bristle border, a dentition, a pro- 
tuberance at an articulation, cannot become thicker, 
longer or stronger by usage, it can only be used up.” 147 
But does not the very use of these inactive parts or, 
better, the transmission through the inert substance to 
the living substance of the mechanical action constituted 
by this repeated use, provoke the living tissue to secrete 
in larger quantity the chitinous substance of the bristles 
and of the claws? 
1467 @ Dantec: Lamarckiens ct Darwiniens. P. 142—145. 
“Weismann: Neue Gedanken zur Vererbungsfrage. P. 65. 
