322 SCIENCE PROGRESS 



It has often been asked, if acquired characters are inherited, or rather 

 accumulated (as I assert they are by Precession, though not through the 

 germ), how is it that artificial mutilations, like the docking of dogs' tails, 

 inflicted for centuries on every generation, show no tendency to be inherited 

 at all ? If the natural loss of characters takes place, as I contend, by Pre- 

 cession, the reply is evident. A mutilation inflicted on every generation in 

 turn at the same age cannot be expected to show any tendency to reappear in 

 posterity at an earlier one. Here then is confirmation of the theory in the 

 shape of an old difficulty simply explained. 



There will, I hope, be no difi&culty in imagining this secular movement 

 of Precession which I believe to be manifested increasingly throughout the 

 ages of organic evolution, but in the hope of making it yet clearer I will avail 

 myself of the best illustration I can think of among familiar movements. 

 Suppose a telescope to be slowly but continuously shut up, but at the same 

 time to have fresh joints of equal length added at frequent and regular 

 intervals of time to the object end. And suppose the shutting to affect 

 all joints equally, and to be at such a rate as not quite to neutralise the effect 

 of the additions. Then clearly the telescope grows very slowly in length, 

 and every joint, because of the additions made at one end only, travels steadily 

 backwards, always shortening as it goes, towards the eye-piece, on reaching 

 which it finally closes up to nothing. The telescope typifies the lives of a 

 series of animals in a single line of descent, and its new joints are each the 

 new characters or additional modifications of a single generation, while its 

 eye-piece is the germ. As it slowly gains in length, so do the most highly 

 developed animals take the longest time in growth and have the longest 

 lives. The movement of the fresh joints towards the eye-piece, always 

 shortening as they go, and their final successive elimination, illustrate the 

 movement of Precession of characters, by which, originally attained at 

 maturity and directed and moulded by the forces of the environment, they 

 end in being attained in the earliest phases of growth, and then passing out 

 of existence altogether. It may be well to add, however, that while the 

 movement of such a telescope would be a real movement of the parts of a 

 single object, that which it typifies is an appearance only, arising, like that 

 of a cinema picture, from the successive presentation to the mind of a series 

 of objects similarly differing from each other. 



It will be seen that I look on the effects of the environment upon a series 

 of animals in a line of descent as being, figuratively speaking, gradually thrust 

 back into the germ by constantly repeated precocity caused by accelerated 

 growth, and the addition by each generation of an adaptation somewhat in 

 advance of its predecessors. And I think the establishment of the movement 

 of Precession will be sure to lead to a revision of opinion as to the rate at 

 which evolution may have proceeded and be proceeding now, especially in 

 the case of those who suppose that all depends on the spontaneous variation 

 of the germ. 



Such then, as well as I can sketch it in bare outline, is the theory of the 

 process of evolution which I pubhshed in September 1920, and I am in no 

 doubt it will eventually be found to show that consonance and concatenation 

 with old-established truths which, with apologies to Spencer, is the only 

 test of the validity of new ones, and to lead to a better understanding of many 

 phenomena of evolution than has hitherto been reached. Indeed, the 

 movement I call Precession harmonises and unifies a great number of ascer- 

 tained facts : those of recapitulation in the early stages of life, those of 

 precocity in the attainment of a full development, those of comparative 

 longevity, and those of the riddance from the species of limbs and organs 

 that have become useless to the individual. Finally it solves the much- vexed 

 problem of the inheritance of acquired characters. Had it been published 

 in the last century at the time when the controversy on that problem ran so 



