Dec, 1903.] Transmission of Acquired Characters. 29 



Obviously, selection of favorable variations is the only explana- 

 tion here. If, then, we must assume that, for instance, the im- 

 mense jaws with the corresponding muscles of the termite soldier 

 are produced by selection, why must we assume a different cause 

 in the case of the antlers of the stag ? When all evidence is 

 weighed, it must be admitted that here is a solution of the prob- 

 lem. 



The problem has been attacked from other points of view. 

 Thus, Henry Fairfield Osborn, in an article in the A /fn'/iavi Nat- 

 uralist^^ .shows the plausability of the transmission of functional 

 changes being the method of evolution in organic life. It is too 

 much to assume, he says, that the tubercles in the teeth of mam- 

 mals have been formed in an}- way other than by the the transmis- 

 sion of mechanical mouldings. Eimer, the friend of Weismann, 

 is the author of an elaborate volume in which he presents an 

 array of facts in support of the transmission theory. He lays 

 special stress on the matter of the pigmentation of the races of 

 man. He finds that in the Nile valley there is a gradation, as one 

 passes from Alexandria southward, in the color of the native 

 races from an intense black to lighter complexions through vari- 

 ous intermediate shades. How, he asks, are we to account for such 

 gradations by the preservation of favorable variations? Is it not 

 more logical to assume that they have been the direct effect of 

 environment from generation to generation ? Eimer' s work is 

 written in German and J. T. Cunningham of England has trans- 

 lated it. This author himself is a firm believer in the transmis- 

 sion hypothesis and is a frequent contributor to the subject. To 

 him is due partly the prominence that the question occupies at 

 the present time. 



We have considered thus far proofs from the a priori point of 

 view and also deductive proofs. There remains but one class of 

 evidence — experimental. The classic experiments of Brown- 

 Sequard on the guinea pig, in which he attempted to show that 

 epilepsy, caused by the severance of the spinal cord in adults was 

 transmitted to the offspring, are now considered invalid since 

 germs of disease may be transmitted in the germ-cells as .syphillis 

 is known to be. There have been thousands of cases reported of 

 the so-called transmission of mutilations. Absolutely no depend- 

 ence can be put on the large majority of these because of insuffi- 

 cient data. Moreover, regeneration is .so general that it is a priori 

 improbable that amputations and the like are ever transmitted. 



The acme of attempts at experimental proof is found in the 

 work of John Cossar Ewart, the Scotchman. The experiments 

 in breeding zebras, horses, sheep, dogs, rabbits, etc., that he has 

 carried out are of the highest type of scientific work. Environed 



* American Naturalist, 23 : 561. 



