102 HYATT ON THE TERTIARY SPECIES 



ation described above, whereas the law of natural selection can only act when there is a 

 choice of characteristics, and where those characteristics are differences, variations newly 

 introduced, not yet fixed in the organization, and unquestionably advantageous. Animals 

 or plants must act and react upon each other, and then and not before then, can we have 

 any law like that of natural selection, and it is exceedingly qviestionable whether natural 

 selection applies at either extreme of life. Man is certainly by his own acts capable of 

 modifying and perhaps controlling the result of the battle of life, and it is very probable 

 that the action and reaction of the first beginnings of life in the past history of the 

 world, was no more than could be accounted for by the known action of physical forces 

 upon the simplest of organisms. 



Natural selection certainly has nothing to do in the embryo, nor yet in the extreme old 

 age of the individual. If, as I have constantly tried to prove, the individual life is a true 

 exponent of the life of the group to which it belongs, the embryo to the progressive past, 

 the adult to the present, and the old age to the degraded or retrogressive future of an 

 exhausted or diseased type, then it may with approximate certainty be assumed that 

 natural selection acts at neither of the extremes of the variation of a given group, neither 

 upon the phenomena of their first appearance, nor upon those indicating their decline and 

 leading to their disappearance. 



Natural selection, in fact, is simply one of the transient conditions of the physical sur- 

 roundings, having no value as a cause of origin of characteristics, but simply acting on 

 certain categories of these characteristics, after they have originated, and helping to take 

 them out of the list of transient charactei'istics and fix them in the organization. Once 

 fixed they are inherited, and, unless as described above, interfered with by a reversal of 

 the ordinary physical conditions, by extreme parasitism, etc., they become a part of the 

 younger stages of growth in accordance with the law of acceleration, and are either finally 

 skipped, crowded out altogether, or become embryonic and part of the type form. 



Herr Wiirtenberger has, also, observed this pecuHarity of the skipping or omission of 

 accelerated characteristics, which originally caused the use of the name acceleration as 

 applicable to these phenomena, and used also in this respect words which are almost iden- 

 tical with those which I have employed in describing the same phenomena in previous 

 essays. 



" Denn es ist leicht einzusehen, dass die fortgesetzte Wirkung der friihzeitigeren Verer- 

 bung der fortwiihrend im Lebensalter auftretenden Abanderungen dahin fiihren muss, die 

 friiheren Entwickelungsstadien naher zusammenzudriingen, zu verwischen oder zum Theil 

 ausiallen zu lassen, wenn die der eigentlichen Entwickelung der Organismen uicht fiber 

 alle Massen hinaus verlangert werden soil." 



" For it is easy to perceive, that the prolonged working of the earlier transmission ^ of 

 the changes which are perpetually appearing in older life ^ must lead the earlier stages 

 of development'^ to shorten up, to disappear wholly or partly, or else the individual devel- 

 opment of the organism would be prolonged beyond all just measure." 



iln successive individuals, forms or species. ^ Of descendant individuals, forms or species. 



' Of the more ancient or ancestral individuals or species. 



