Professor Henri Bergson’s Biology. 87 
certain aspect of evolution. Thus Darwinism is sound in its recognition of a 
continual crop of germinal variations which Nature sifts, but its designation 
of these variations as accidental must be modified. 
The idea of definite variations continuing cumulatively in one direction 
generation after generation—the theory of orthogenesis, in fact—is also 
accepted as applicable to certain cases. But it is apt to be exaggerated into a 
denial of spontaneity. 
The Lamarckian view that the effort of the organism counts for much in 
evolution has a big truth in it, but the transmission of the results of changes 
of function is certainly not the rule, and the effort that really tells is not 
individual, but, so to speak, racial and germinal. 
“A hereditary change in a definite direction, which continues to 
accumulate and add to itself so as to build up a more and more complex 
organism, must certainly be related to some sort of effort, but to an effort of 
far greater depth than the individual effort, far more independent of circum- 
stances, an effort common to most representatives of the same species, 
inherent in the germs they bear rather than in their substance alone, an 
effort thereby assured of being passed on to their descendants.” This 
expresses one of Bergson’s fundamental ideas,—the conception of an original 
vital impetus, sustained right along different lines, the fundamental cause of 
variations. 
In regard to the much-debated question of the possible transmission of 
individual modifications, 2.c. bodily changes directly induced by changes in 
function or in environment, Bergson makes an ingenious suggestion, One of 
the few known cases worth considering on the affirmative side is that of 
Brown-Séquard’s guinea-pigs in which he quite artificially induced a sort of 
epilepsy, with the result that some of the offspring were specifically affected. 
Bergson suggests that the morbid condition may have produced specific cyto- 
toxins which affected the germ-cells specifically. Might not the same be true 
of some acquired characters? May not the modification—a deep one of 
course—liberate a specific substance which affects the germ-cells, and in 
development affects the primordium of the structure corresponding to that 
which was modified in the parent ? 
Bergson gives great prominence to a familiar but inadequately studied 
fact, technically called convergence,—a structural resemblance in organisms 
belonging to unrelated groups. The two structures that resemble one 
another in these widely separated types must have evolved independently,— 
and that is the puzzle. The matter has been recently discussed in a very 
interesting book by Prof. Arthur Willey. 
Why is it that Bergson is so much interested in convergence? Why 
