44 Experimental Zoology 



the evidence is not satisfactory in all respects. He states that 

 certain aberrations, that occur when the external factors have 

 produced a sudden divergence from the parent form, are in- 

 herited. He shows by numerous experiments that these aber- 

 rant forms when crossed with the parent type do not give 

 intermediate varieties, but that the offspring correspond to one 

 or to the other parent. Thus the new type is not lost by inter- 

 crossing; but if adaptive, might perpetuate itself and form the 

 beginning of new species. 



The aberrations seem to resemble in these respects mutations. 

 If they are really produced by a change in the environment, as 

 Standfuss believes, the results throw most important light on 

 the question of the origin of mutations a question which at 

 the present time is one of the most pressing questions of the 

 theory of organic evolution. 



Standfuss believes that effects of these kinds are inherited, 

 and that new species may be evolved at the limits of the range 

 of forms through the effect of external agents. It is not quite 

 clear to me, how he supposes such results come about, since 

 his own experiments seem to show that the effects of moderate 

 changes in temperature are only temporary. He appears to 

 believe, however, that the effects, if long enough carried out, 

 become in large part fixed. 



In plants the effects of the environment on the form, growth, 

 and time of flowering have long been known; and many ex- 

 periments have been made by transporting plants from one 

 locality to another. It has been shown that many alpine plants 

 will flourish in the valley, and often great changes in the char- 

 acter of the plants have been noted. Naegeli has carried out 

 elaborate experiments of this sort. He collected in the Botani- 

 cal Garden of Munich 2500 varieties of mountain plants, and 

 for several years made observations on the effects of changes 

 in the environment. The changes are seen at once, showing 

 that no permanent effects have been produced by the alpine 

 climate. Other botanists, however, claim that for a time at 

 least the effect of the original habitation may be seen. 



