xxiv Unconscious Memory 



In 1901 Hugo De Vries, Professor of Botany in the 

 University of Amsterdam, published " Die Mutations- 

 theorie," wherein he showed that mutations or dis- 

 continuous variations in various directions may appear 

 simultaneously in many individuals, and in various 

 directions. In the gardener's phrase, the species may 

 take to sporting in various directions at the same time, 

 and each sport may be represented by numerous speci- 

 mens. 



De Vries shows the probability that species go on for 

 long periods showing only fluctuations, and then suddenly 

 take to sporting in the way described, short periods of 

 mutation alternating with long intervals of relative con- 

 stancy. It is to mutations that De Vries and his school, as 

 well as Luther Burbank, the great former of new fruit- and 

 flower-plants, look for those variations which form the 

 material of Natural Selection. In " God the Known and 

 God the Unknown," which appeared in the Examiner 

 (May, June, and July), 1879, but though then revised was 

 only published posthumously in 1909, Butler anticipates 

 this distinction : — 



" Under these circumstances organism must act in one or 

 other of these two ways : it must either change slowly and 

 continuously with the surroundings, paying cash for every- 

 thing, meeting the smallest change with a corresponding 

 modification, so far as is found convenient, or it must put off 

 change as long as possible, and then make larger and more 

 sweeping changes. 



" Both these courses are the same in principle, the differ- 

 ence being one of scale, and the one being a miniature of the 

 other, as a ripple is an Atlantic wave in little ; both have 

 their advantages and disadvantages, so that most organisms 

 will take the one course for one set of things and the other 

 for another. They will deal promptly with things which they 

 can get at easily, and which lie more upon the surface ; those, 

 however, which are more troublesome to reach, and lie deeper, 

 will he handled upon more cataclysmic principles, being allowed 

 longer periods of repose followed by short periods of greater 

 activity ... it may be questioned whether what is called a 



