28 SCIENCE PROGRESS 



University of Cambridge, as early as 1894 laid great stress 

 on the importance of discontinuous variations, collecting and 

 collating the known facts in his Materials for the Study of 

 Variations ; but this important work, now become scarce and 

 valuable, at the time excited so little interest as to be " re- 

 maindered " within a very few years of publication. 



In igoi Hugo De Vries, Professor of Botany in the University 

 of Amsterdam, published Die Mutationsthcoric, wherein he showed 

 that mutations or discontinuous 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 specimens, 



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 constancy. 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 afford the material of Natural 

 as of Human 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 in 1909 

 post-humously — Butler anticipates this distinction : 



" Under these circumstances the organism must act in one or 

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

 tinuously with the surroundings, paying cash for everything, 

 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 modifications. 



" Both these courses are the same in principle, the difference 

 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, how- 

 ever, zvhich are more troublesome to reach, and lie deeper, will be 

 handled npon more cataclysmic principles, being alloived longer 

 periods of repose followed by short periods of greater activity. ... It 

 may be questioned whether what is called a sport is not the 

 organic expression of discontent which has been long felt, but 

 which has not been attended to, nor been met step by step 



