1896.] Variation after Birth. 17 



account of their greater usefulness and superior adaptability 

 ultimately interfere with the development of the less useful an- 

 cestral stages and thus tend to replace them. The necessary 

 corollary of this process would be tachygenesis or earlier appear- 

 rance of the ancestral stages in direct proportion to the number 

 of new characteristics successively introduced into the direct 

 line of modification during the evolution of a group. 



If this be true, it can hardly be assumed that the loss of 

 characteristics and parts taking place in this way is directly 

 due to growth force. If growth has anything to do with these 

 phenomena, it must act indirectly, and, as in the repetition of 

 other similarities and parallelisms, under the controlling guid- 

 dance of heredity. 



VARIATION AFTER BIRTH. 



By L. H. Bailey. 



At the present time, our attention is directed to differences 

 or variations which are born with the individual. We are 

 told that variation which is useful to the species is congenital, 

 or born of the union — or the amalgamation in varying de- 

 grees — of parents which are unlike each other. From the 

 variations which thus arise, natural selection chooses those 

 which fit the conditions of life and destroys the remainder. 

 That is, individuals are born unlike and unequal, and adapta- 

 tion to environment is wholly the result of subsequent select- 



These are some of the practical conclusions of the NeoDar- 

 winian philosophy. It seems to me that we are in danger of 

 letting our speculations run away with us. Our philosophy 

 should be tested now and then by direct observation and ex- 

 periment, and thus be kept within the limits of probability. 

 The writings of Darwin impress me in this quality more than 

 in any other, — in the persistency and single-mindedness with 

 which the author always goes to nature for his facts. 



