448 Transactions of the Society. 



fact that, frequent as variations are, hereditary constancy, or 

 inertia, or persistence of specificity is even more marked. The 

 followinfT susf^estions are before us. That oerminal disturbances 

 come about in response to subtle environmental stimuli of a 

 novel kind penetrating in from without and affecting the chromo- 

 somes, or perhaps the " mysterious karyolymph or gel which forms 

 the groundwork of the nucleus." Along with definable changes 

 in the external environment may be included changes in the 

 somatic fluids which might affect the nutritive or other metabolism 

 of the serm-cells. That in the divisions of the germ-cells before 

 fertilization, where there has to be a partition of a complex cyto- 

 plasmic and chromosomic cargo between two vessels, losses and 

 augmentations and inequalities may be expected in the tranship- 

 ment. That in fertilization with its intimate and orderly union 

 of paternal and maternal contributions (amphimixis) there may be 

 opportunity for new permutations and combinations, the result 

 normally being a viable unity of dual origin. That there may 

 be growth-changes, or regulative re-organization processes, or 

 rejuvenescences in the germ-cells in the course of their history ; 

 and it is possible that there may be something in Weismann's 

 hypothesis of intra-gerininal struggle. 



§ 11. We are thus aware of certain originative factors in evolu- 

 tion, which admit of experimental testing, and we should not lose 

 sight of any of them. Each must be pushed as far as it will go. 

 Iiecognizing this, some will insist that there is no more to be said, 

 but much to be done. We venture to doubt, however, whether 

 this is not making a tyranny of scientific method (which, after all, 

 is very selective and partial), and giving up the right of speculative 

 adventure. As the great Kussian embryologist von Baer said : 

 there is observation, but there is also reflection. 



Those who have devoted much attention to the occurrence of 

 variations — we think, for instance, of Darwin and Bateson — have 

 given emphatic expression to their sense of the difficulty of account- 

 ing for the origin of the new. The fountain of change, whence 

 are its well-springs ? But we also notice that some of those who 

 have given much of their life to the studv of the phenomena of 

 variation occasionally lapse from the stern path of science, and m 

 face of the difficulty of the problem ask themselves if they are 

 allowing enough for the fact that the organism is alive. Thus we 

 would quote from the recent work of Dr. E. E. Gates, on " The 

 Mutation Factor in Evolution," this interesting sentence : " Just 

 as an Alpine climber dangling over a chasm may, by changing his 

 hold, swin" himself on to a shelf from which he can make a fresh 

 start in some other direction, so we may think of the organism 

 trying many unconscious experiments in its offspring, some of 

 wiiich are hurled by the gravitational effect of natural selection 



