Febebakt 3, 1911] 



SCIENCE 



lib 



of the other extreme, so that the various types 

 gradually arose. 



The great Biblical Pharaoh Rameses II. had a 

 prominent, slender nose not now found in any 

 Egyptians, and it is a positive proof of the recent 

 arrival of some ancestor from the north. He vras 

 lilce Lord Cromer — a northern type ruling a na- 

 tive type. 



Allen^° has called attention to a correla- 

 tion between climate and the color of birds. 



The increase in color towards the south coin- 

 cides with the increase in the intensity of the 

 sun's rays and in the humidity of the climate. 

 The increase in color observed in birds on passing 

 from east to west [in the United States] seems 

 also to coincide with an increase of humidity, 

 " the darker representatives of any species occur- 

 ring where the annual rainfall is greatest, and 

 the palest where it is least." This coincidence 

 occurs not only in the birds of the United States 

 to such a degree that Allen says he knows of no 

 exception, but in Europe also. Thus birds from 

 the Scandinavian coast are very much darker 

 than in central Europe, where the rainfall is only 

 half as great. Allen says that this correlation of 

 brighter and deeper tint with increased humidity 

 is exhibited by the mammals of these districts 

 as well as by the birds. 



NON-ADAPTABILITY 



While the theorem of Le Chatelier 

 enables us to account for the direction of 

 a change, it does not tell us whether a 

 given stimulus will actually produce a 

 change or under what condition the change 

 will be a maximum for the same stimulus. 

 We can make a fair guess at the answer by 

 studying ourselves. We know that, as we 

 get older, our tendency to resist change in- 

 creases; our habits of body and mind be- 

 come more fixed. We should therefore be 

 tempted to conclude that the resistance to 

 change increases as the organism becomes 

 mature and that a given stimulus would 

 probably have the most effect if applied at 

 or before the earliest stages of develop- 

 ment. The following quotation from Ver- 



" Vernon, " Variations in Plants and Animals.' 

 327, 1903. 



non''^ would seem to indicate that this was 

 often true. 



Due reflection, will, I believe, incline one to 

 infer that what is true for echinoid larvje is true 

 for most multicellular organisms. In fact, it 

 would seem to be a law of general application 

 that the permanent effect of environment on the 

 growth of a developing organism diminishes rap- 

 idly and regularly from the time of impregnation 

 onwards. 



It is curious that this principle, enunciated by 

 the author in 1900, should have been laid down 

 by De Vries only a few months later, as the result 

 of his observations on plants. Thus, judging from 

 the efiects of nutrition (manuring, planting out, 

 good light and watering), he concluded that: 

 ( 1 ) the younger 'a plant is, so much the greater 

 is the influence of external conditions on its 

 variability. (2) The nutrition of the seed, when 

 developing on the maternal plant, has — at least 

 very often — a greater influence on the variability 

 than nutrition during its germination and later 

 growth. 



If the pressure on a liquid is made less 

 than the vapor pressure for that liquid 

 at that temperature, some of the liquid 

 vaporizes, the temperature falls, and the 

 liquid may be said to adapt itself to the 

 new conditions. What would happen if 

 the liquid were not adaptable? The 

 easiest way to obtain a non-adaptalale 

 liquid is to place a Bunsen burner under it. 

 The temperature rises until the boiling- 

 point is reached. The liquid then ceases to 

 be adaptable. It volatilizes, it disappears, 

 it becomes extinct so far as that particular 

 region or flask is concerned. If a species 

 can not adapt itself to changed climate or 

 other conditions, it does not volatilize ; but 

 it disappears, it becomes extinct. It may 

 be a new point of view to consider the ex- 

 tinction of the mastodon as analogous to 

 the distillation of water; but the two cases 

 are really parallel, except in time. 



It should be kept in mind that non- 

 adaptability is not the only cause for ex- 



"■ " Variation in Animals and Plants," 199, 

 1903. 



