A MEDLEY OF PUMPKINS. 121 



very fact that Mendel chose his stock plants with such great care, selecting 

 species which are relatively invariable, that do not intercross, and that he 

 eliminated the weak and abnormal plants, would tend to give uniformity in 

 the results. We are in danger of becoming partisans. Professor Bailey re- 

 marked that he neither believed nor disbelieved in Mendel's laws. He de- 

 sired only to know what the truth is. He thought that future experiments 

 should be carried on along the lines suggested by Mendel, and not for the 

 purpose of proving or disproving his conclusions. 



It has recently been said that the time is rapidly coming when we can 

 predict the results of hybridization with certainty, and can produce new 

 varieties of plants with almost no element of chance. This hope is far too 

 sanguine. Mendel's laws come from a contrast and comparison of specific 

 differentiating characters. It is not so much a contrast of plants as a 

 contrast of single characters of those plants. In ordinary crossing it will 

 often be impossible to secure plants that have differentiating characters. 

 What the plant breeder wants is a plant in its entirety rather than a plant 

 with specific attributes alone ; that is to say, it may be possible to secure 

 some character that is wanted, but with this desired character undesirable 

 ones of other kinds may be associated. Furthermore, Mendel's results 

 show that the offspring of hybrids are not intermediates or new kinds, but 

 that they are controlled by the characters of one or the other of the parents, 

 so that new forms may not arise as a result of crossing. Every plant has 

 unknown and unrecognizable characters, attributes that we refer in a loose 

 way to the "constitution" of the plant. Moreover, one does not know in ad- 

 vance what characters will become dominant and which will be recessive. 

 In other words, ISIendel's law must be applied and discovered for each kind 

 of plant; and the probabilities are that the results will be considerably modi- 

 fied by the conditions under which the plants grow. Again, the uniformity 

 in Mendel's results was secured by the average totals of a great number of 

 plants. The individual plants often varied widely in the very characters 

 which in the average totals were relatively invariable in behavior. Now, the 

 starting point of a new variety must be one individual plant, and not the 

 average of a hundred or a thousand. The general results may be predicted 

 with some degree of certainty, but how the individual plants will stand 

 with reference to that result will be unknown. The practical value 

 of Mendel's work to the actual plant breeder is yet in doubt, but the value 

 of these remarkable experiments in elucidating our notions of hybridity, and 

 in systematizing experiments, may be beyond calculation. 



Professor Bailey also spoke of the recent philosophy of De Vries and 

 his associates. Heretofore our thought has been dominated very largely 

 by the Darwinian principle ; that is, it is supposed that great differences may 

 come about because small differences are enlarged by means of natural or 

 artificial selection— a variety may become more of a variety. The new notion 

 is that the important and permanent forms of plants come about as sudden 

 sports or jumps, and that the small individual variations are incapable of 

 growing into large and permanent varieties by means of natural selection. 

 De Vries does not deny the power of natural selection, but he believes that 

 its range is limited, that it cannot give rise to species, and that it does not 



