June 12, 1896.] 



SCIENCE. 



855 



est, must take place between the various 

 species of biophoi-es as well as between the 

 species of determinants. Bj^ the continued 

 weakening of a biophore until it ultimately 

 disappeared the quality of the determinant 

 to which it belonged would be changed. 

 Tlie ultimate cause of all variations in hind is, 

 therefore, clue to the varying amount of nutri- 

 ment supplied to the biophores. 



4. " Every determinant battles stoutly 

 with its neighbors for food." 



5. The weaker determinant " will be un- 

 able to obtain the full quantum of food * * 

 * * and the result will be that its progeny 

 will be weakened still more * * * and in- 

 evitably the average strength of this deter- 

 minant must slowly but constantly dimin- 

 ish." 



6. The stronger determinants " oppose a 

 relatively more powerful front to their 

 neighbors, that is, actively absorb more 

 nutriment, and upon the whole increase in 

 vigor and produce more robust descend- 

 ants." 



7. The plus and minus variations may go 

 on simultaneously and independently in 

 many groups of determinants. When in 

 any case they have reached selection valne 

 they may be checked or increased by per- 

 sonal selection. " In this manner it be- 

 comes intelligible how a large number of 

 modifications, varying in kind and far more 

 so in degree, can be guided simidtaneously by 

 personal selection." 



The possible application of some of these 

 principles is illustrated by cases of mimicry 

 shown in the wings of butterflies, and the 

 necessity of retaining the principle of natu- 

 ral selection to explain mimicry and adap- 

 tations in general is ably shown. In con- 

 clusion the author says : " We had applied 

 the principle of natural selection to a part 

 of the natural units engaged in struggle. If 

 we apply the principle throughout we reach 

 a satisfactory explanation. Selection of 

 persons alone is not sufficient to explain the 



phenomena ; germinal selection must be 

 added. Germinal selection is the last con- 

 sequence of the application of the principle 

 of Mai thus to living nature." ;|; ;ic * "This 

 proposition seems to me to round off the 

 whole theory of selection and to give it that 

 degree of inner perfection and completeness 

 which is necessary to protect it against the 

 many doubts which have gathered around 

 it on all sides like so many lowering thunder 

 clouds." 



Eegarding Weismann's recent conces- 

 sions to his opponents, it should be observed 

 that he does not make them until having 

 gotten a new foothold on the piinciple of 

 germinal selection he can afford to yield 

 these points. He nowhere makes adequate 

 acknowledgment of the force of the facts 

 urged against natural selection, nor the in- 

 sufficiency of the latter until he feels sure 

 that he can save his pet theory by another 

 theory. In short, it would appear that with 

 him the all-sufficiency of natural selection 

 is a foregone conclusion, and however 

 weighty the arguments may be which are 

 brought against his position he disregards 

 them until he is able to explain them in con- 

 formity with liis theorjr. 



This new hypothesis of germinal selection 

 is a bold attempt to explain the causes of all 

 variations and the usefulness, or adaptive 

 character, of many variations upon the se- 

 lection principle. With such high aims it 

 is an extremely important contribution, 

 whatever may be thought of its probability. 

 To the writer it seems that Weismann fails 

 to recognize that the ' selection ' which he 

 predicates of determinants and biophores is 

 a wholly different principle from the natu- 

 ral selection of Darwin and Wallace. Both 

 natural and artificial selection signify that 

 in the struggle for existence certain indi- 

 viduals and races are selected and others re- 

 jected. If the unfit should survive and leave 

 as many offspring as the fit there would cer- 

 tainly be no such thing as natural selec- 



