VARIATION AND MUTATION 151 



attained by controlling the environment (kind and quantity of food, 

 degree of temperature, humidity, and light, etc.), but if such variations 

 (modifications) acquired during development are not inherited, there 

 will be no advance, generation after generation, along any line. There 

 will be no cumulative effect of such determinate variation. The con- 

 stant repetition of a certain environment on generation after genera- 

 tion of a certain species would of course produce a constant repetition 

 of certain individual modifications (orthoplasy), but we do not know as 

 yet of any actual effect on the species of such persistent ontogenic 

 variations. 



"The need, however, for some such factor in species-forming as de- 

 terminate variation is obvious and strongly felt. There are certainly 

 few selectionists left who honestly believe that the minute fluctuating 

 variations in pattern, in size, in curve of a vein, in length of a hair, etc., 

 have that life-and-death value which is the sole sort of value that an 

 4 advantageous variation ' must have to be a serviceable handle for the 

 action of natural selection. As a matter of fact, no systematist will 

 have escaped having had it distinctly impressed on him that he recog- 

 nizes differences in the pattern of ladybird beetles, in the number of 

 fin rays in fishes, in the branching of a vein in flies' wings, that no 

 enemy, no agent of natural selection, can recognize, at least to the 

 extent of pronouncing sentence of death (or not pronouncing it) on 

 its basis. And further, no biologist really satisfies himself with the 

 worn statement: ' We must not presume to judge the value of these triv- 

 ial, these microscopic differences, for we do not know all the complex 

 interrelation and interaction of the organism and its environment.' 

 We do not ; but we do know for many cases that such differences are 

 not actually of life-and-death selective value, and reason compels us to 

 believe to a moral certainty that in other cases these fortuitous trivi- 

 alities have similar lack of life-and-death importance. 



" Directly touching this point are our data of the variation of series 

 of honey bees collected from free-flying individuals after exposure 

 as adults to the rigors of outdoor life, as compared with the variation 

 in the series of bees, adults, but collected just when issuing from the 

 cells before being exposed as adults in any way to the external dangers 

 of living. Series of both drones and workers representing both exposed 

 and uncxposcd individuals were studied. The results of this examina- 

 tion are, that the variation among the exposed individuals is no less 

 than that among the unexposed individuals. This means that these 

 various, mostly slight, blastogenic, variations (although in such im- 

 portant organs as the wings), which occur among bees at the time of 



