226 HISTORY OF BOTANY 



Ten years after the publication of Weismann's dis- 

 turbing theories one of our chief English authorities on 

 such problems, Bateson (from whose writings I am freely 

 quoting) drew attention to the fact that species do not 

 merge gradually into each other, but that there is always 

 more or less marked discontinuity. How can this 

 discontinuity be accounted for if the process by which 

 species have arisen is one of accumulation of minute 

 and almost imperceptible differences ? Why are not 

 intermediates of all sorts more abundantly produced in 

 nature than is actually known to be the case ? These 

 criticisms seemed to be met to some extent by De Vries, 

 who, in 1901, published an important work on what he 

 termed Mutations. From a long study of Oenothera, 

 the " evening primrose/' he came to the conclusion that 

 new varieties might spring into being at a bound, so to 

 speak, and his work raised the suspicion that variation 

 might be discontinuous and not due to the slow accumula- 

 tion of infinitesimal additions. Were such a view accepted, 

 it followed that it would be necessary to alter entirely 

 our views on the doctrine of evolution as propounded 

 by Darwin in 1859. 



It was at this time, when our notions on heredity and 

 variation had been so rudely shaken and thrown once 

 more into the melting-pot, when, as Bateson says, " in 

 the study of evolution, progress had well-nigh stopped, 

 when the more vigorous, perhaps also the more prudent, 

 had left this field of science to labour in others where 

 the harvest is less precarious or the yield more immediate, 

 when of those who remained some still struggled to push 

 towards truth through the jungle of phenomena, whilst 

 most were content supinely to rest in the great clearing 

 Darwin made long since " it was at this moment that 

 a name burst upon the biological world that has now 

 become familiar to every student of the science the 

 name of Mendel. 



Gregor Johann Mendel was born in 1822 in Austrian 



