DECEMBER 17, 1897. ] 
I dare say that the above definitions will 
be objected to by some of my readers, but 
Iamin hopes that, on consideration of what 
follows, the majority will assent to them as 
indicating pretty correctly what we really 
mean by the terms ‘inborn’ and ‘ acquired.’ 
I do not here propose to discuss the ques- 
tion as to whether acquired modifications 
are transmissible; I have done it at length 
elsewhere, and my present object is rather 
to differentiate accurately between the ac- 
quired and the congenital, and to ascertain 
the parts played by them respectively in 
the organic world. JI may, in passing, how- 
ever, notice one or two points which have 
been frequent sources of confusion and the 
consideration of which may help to bring 
the meaning [intend my definitions to bear 
clearly before the mind. 
It has often been maintained by Neo- 
Lamarckians that important modifications 
in the soma (e. g., the effects of disease) 
must affect the associated germ cells, and 
that therefore acquired modifications must, 
to some extent, be transmissible.** They 
miss the point at issue. It is not denied 
that changes in the germ’s environment (7. 
e., in the body of the parent) may result in 
modifications in the organism into which 
the germ subsequently proliferates, but it 
is strenuously denied that acquired modifi- 
cations in the parent tend specially so to 
modify the germ as to cause the organism 
into which it subsequently proliferates to 
reproduce congenitally the particular modi- 
fication which the parent acquired. Again, 
supposing some cause (é. g., disease) pro- 
duced a modification (e. g., cavities in the 
lungs) in the soma and that subsequently, 
in the absence of the cause, the offspring 
* “The germ is a unicellular organism and there- 
fore it should be modifiable in accordance with its 
environment. Such environment would be different 
in the body of a sedentary clerk and a hard-working 
agricultural laborer, and on this hypothesis the off- 
spring in these cases would be different.’’ (S. S. 
Buckman, Natwral Science, March, 1897, p. 189.) 
SCIENCE. 
897 
developed the modification; even this 
would not constitute an absolute proof of 
the Lamarckian doctrine, though it would 
raise a presumption in favor of it. For it 
must be remembered that it is not asserted 
that a force acting on an organism cannot 
produce such a change in the germ as will 
cause the organism into which it develops 
to exhibit a variation similar to the modi- 
fication produced by the force in the parent, 
but that it is asserted that this coincidence, 
this mere coincidence, must, from the nature 
of the case, be extremely rare, so very 
rare that, as factors in evolution, such ap- 
parent, but only apparent, transmission of 
acquired traits may practically be ignored. 
Only after it had been shown that clear and 
indubitable cases of reproduction by the 
offspring of the parents’ modification were 
not uncommon in nature could the truth of 
the Lamarckian doctrine be accepted as 
proven. 
Watching the multiplication of an in- 
fusorian (Stylonychia Pustulata), Maupas 
observed that, after two of these had con- 
jugated, the resulting fertilized cell divided 
and redivided many times without conjuga- 
tion again occurring, but that if, after a 
certain pretty definite number of cell-di- 
visions, conjugation did not again occur, 
the race ultimately died out. He found, 
moreover, that the descendants of a conju- 
gated pair did not conjugate among them- 
selves, but only with the descendants of 
another conjugated pair. All this is the 
rule among higher plants and animals. 
The ovum and the sperm are unicellular 
organisms. After conjugation they divide 
and redivide many times without conjuga- 
tion again occurring among the descendant 
cells. But these, like the infusorians, if 
they do not conjugate, ultimately die out. 
Most of them (4. e., the somatic cells) are 
incapable of conjugation, while such of 
them as are capable of conjugation (i. e., 
the germ cells) conjugate only with cells 
