58 



TRANSACTIONS OF THE ILLINOIS 



shall, indeed, find a wide and a rich field for investigation, if we look 

 into their history, study their inner life, look to the manner in which 

 they are distributed, and learn how they are afiected by the varying 

 conditions with which they are sun'ounded. 



In nature we find tiiat plants are singularly distributed. Here, in the 

 prairie region, the grasses, low, herbaceous plants prevail; beside the 

 streams alone do we find the taller timber-producing families of plants, 

 and these are here almost exclusively deciduous, while in other regions 

 the whole surface of the country was naturally clothed with forests of 

 majestic trees, and of these some have deciduous leaves, while others are 

 evergreens. Look where we may, we shall, indeed, be struck with the 

 richness of the variety of these interesting objects of our care and study, 

 which can not fail to force the observer reverentially to acknowledge the 

 existence of an All-wise Creator. 



If we take a more limited sun'ey of the plants under our immediate 

 care or observation, however, we shall find variety also in this more 

 contracted sphere; and it is particularly to the variations found in some 

 of our cultivated plants, that your attention is invited this evening, 

 when, by the request of your Executive Committee, I shall endeavor to 

 discuss a few of the points connected with the ii/iprovemetzt of our fruits 

 by human selectio?z, from among the curious variations that are observed 

 in some of them. 



First, then, let us ask what are these variations? in what do they 

 consist.'' and afterward it may be well to inquire into their cause, or 

 causes. We may ask under what circumstances tliey most frequently 

 occur, and thus endeavor to learn how we may produce desirable changes, 

 and how we can avoid those modifications which are undesirable, or 

 even pernicious. 



Variations consist in any divergence from M'hat has been assumed 

 to be the normal type of the species. These may be manifested in the 

 habit of the plant, or in the mode of its growth — in the shape and other 

 characters of its foliage, as in the Ring-willow — in the style of its 

 inflorescence, as in the varying form and coloration, or in the modifica- 

 tion and multiplication of the parts, as in double flowers — in the color, 

 shape, form, and flavor of the fruit and seeds, as is fully exemplified in 

 our orchards. 



Thus it will be observed that variations consist in modifications of 

 the non-essential characters, and that they must ever be confined within 

 very narrow limits. If these were transcended, we should have a new 

 species, whereas, in varieties, how dissimilar soever they may appear, the 

 true specific characters always remain, though there be hybrids, which 

 may come under our notice as variations, that will present some of the 

 characters of two species. 



For convenience of classification, plants with similar variations from 

 the specific type are arranged in groups as sub-species, races, families, 

 strains, and breeds, borrowing terms familiar to tlic breeders of cattle. 



The definition of the w^ord species has always been difficult, and it 

 is yet a nice matter to say exactly what constitutes a sj^ecies. The broad 



