Cross- Breeding and Hybridizing. 13 



or gardener at ths present day feels that an occasional change of seed re- 

 sults in better crops, and there are definite records to show that such is often 

 the case. In fact, I am convinced that much of the rapid improvement in 

 fruits and vegetables in recent years is due to the practice of buying plants 

 and seeds so largely of dealers, by means of which the stock is often 

 changed. Even a slight change, as between farms or neighboring villages, 

 sometimes produces marked results, as more vigorous plants and often more 

 fruitful ones. We must not .suppose, however, that because a small 

 change gives a good result, a violent or very pronounced change gives a bet- 

 ter one. There are many facts on record to show that great changes often 

 profoundly influence plants, and when such influence results in lessened 

 vigor or lessened productiveness we call it an injurious one. Now, this in- 

 jurious influence may result even when all the conditions in the new place 

 are favorable to health and development of the plant; it is an influence 

 which is wholly independent, so far as we can see, of any condition which 

 interferes injuriously with the simple processes of growth. Seeds of a native 

 physalis or husk-tomato were sent me from Paraguay in 1889 by Dr. Thomas 

 Morong, then traveling in that country. I grew it both in the house and out- 

 doors, and for two generations was unable to make it set fruit, even 

 though the flowers were hand-pollinated ; yet the plants were healthy and 

 grew vigorously. The third generation, grown out-doors this year, set 

 fruit freely. This is an instance of the fact that very great changes of 

 conditions may injuriously affect the plant, and an equally good illustration 

 of the power to overcome these conditions. Now there is great similarity 

 between the effects of slight and violent changes of conditions and small and 

 violent degrees of crpssing, as both Darwin and Wallace have pointed out, 

 and it is pertinent to this discussion to endeavor to discover if there is any 

 real connection between the two. 



It is well proved that crossing is good for the resulting offspring, because 

 the differences between the parents carry over new combinations of charac- 

 ters or at least new powers into the crosses. It is a process of revitaliza- 

 tion. And the more different the stocks in desirable characters within the 

 limits of the variety, the greater is the revitalization ; and frequently the . 

 good is of a more positive kind, resulting in pronounced characters which 

 may serve as the basis for new varieties. In the cross, therefore, a new 

 combination of characters or a new power fit it to live better than its 

 parents in the conditions under which they lived. In the case of change of 

 stock we find just the reverse, which, however, amounts to the same thing, 

 that the same characters or powers fit the plant to live better in conditions 

 new to it than plants which have long lived in those conditions. In either 

 case, the good comes from the fitting together of new characters or powers 



