ATMOSPHERIC FACTOR IN EVOLUTION. 299 



And yet Professor Thomson states : 



" We do not know of any clear case which would at present warrant the 

 assertion that an acquired modification is ever transmitted from parent to 

 offspring." 



So we see that nowadays it is not believed that exogenous 

 modifications are inherited. My first objection then to Darwin 

 is that he assumes the transmission of exogenous modifications. 

 It is merely an assumption. He makes no attempt to prove it. 



(2) He cannot explain the surviving of those varieties or 

 modifications which he says survive. In one passage, in dis- 

 cussing the development of the eye, he says : 



"We must suppose that there is a power always intently watching each 

 slight accidental alteration in the transparent layers and carefully selecting 

 each alteration which may in any way tend to produce a distincter image." 



Here he pictures the Deiis ex machina as watching to see 

 what variations may accidentally crop up, just as a gardener 

 watches his bed of young seedhng flowers. In another passage 

 he says : 



" I have sometimes spoken as if the variations had been due to chance. 

 This of course, is a wholly incorrect expression ; but it serves to acknowledge 

 plainly our ignorance of the cause of each particular variation." 



In another passage he again confesses to this same ignor- 

 ance. He says : 



" We are profoundly ignorant of the causes producing slight variations." 

 My second objection is then that Darwinism can give no 

 explanation of the survival of the fittest. 



I will now consider my new theory, and return later to fur- 

 ther objections to Darwin's, when I will be able to compare the 

 working- of the two. 



By way of introduction to my theory, let me consider the 

 power which animals admittedly have of regulating the heat of 

 their bodies. This is explained by saying that these animals 

 have a heat regulating centre in the brain. Due to this heat 

 regulating centre, the temperature of our bodies is about the 

 same, in the hottest day of summer and the coldest night of 

 winter. Plants, too, have iWs heat regulating mechanism. 

 They keep their temperature down in hot weather by increasing 

 the evaporation. The splitting up of carbon dioxide into carbon 

 and oxygen, besides being a nutritive process, is also a heat 

 regulating one. In this process of splitting up carbon dioxide 

 into carbon and oxygen heat becomes latent, and has to be got 

 from the plant and its surroundings. 



I go even further and state, that not only in every living- 

 organism is there a heat regulating process going on, but we 

 have it too in the inorganic world. Let us consider the act of 

 burning, as in an ordinary coal fire. There is a popular idea 

 that a fire burns best on a cold, frosty night, and that the sun 

 shining on a fire tends to put it out. I remember when I was a 

 student of Edinburgh University, in the Natural Philosophy 

 classroom someone handed up a question on this point to Prof. 

 Tait. He pooh-poohed the idea of the sun tending to put out 

 the fire. He said the heat and light of the sun caused us to 



