INFLUENCE OF CLIMATE ON PLANTS AND ANIMALS. 229 



neous : if, however, the phrase is designed to convey or express the fact, that in the system 

 to which they belong, some species occupy a higher position than others, or that there are 

 grades of development, some of which are high and others low, it is undoubtedly true. The 

 position which a species holds is positive and arbitrary : species occupy a shelf or platform, 

 which is fixed, and it neither inclines downward or upward ; the position of the shelf, or in 

 other words, the species is nearer one than another species, that is, a species more closely re- 

 sembles certain species than others. Although the distance between neighboring species is 

 unequal, still the two which are nearest akin never coalesce with each other through their va- 

 rieties ; even in vegetables, where they are susceptible of being engrafted or budded upon each 

 other, there is no tendency to coalesce, or to produce an intermediate variety ; the scion of 

 the pear engrafted upon the quince is still a pear. There is, to be sure, a good reason for this, 

 the pear is developed or formed in the cellular system, and really bears no connection with the 

 quince, except by the sap, which flows upward and passes through the cellular system. The cells 

 produced are only pear cells, yet it seems that if there was any tendency in the pear to become 

 a quince, under any circumstances, the relation which the scion bears to the stock would be a 

 favorable one. It appears necessary that a cell should be furnished from one of the parents, in 

 order to produce an intermediate progeny, as is the case in the propagation of mules. But 

 here we have unfailing test of the mixed parentage, from the sterility of the offspring, and al- 

 though attempts have been made to prove the contrary position, still there is now no position 

 better established than the one that the offspring of two different species of animals are sterile. 

 .It is true that, as in many other cases, there are partial exceptions, still two mules can not 

 propagate a race. 



Specific character is unchangeable, and species are kept, in consequence of this arrangement 

 strictly apart. There is an application of this fact to the products of our fields, which by 

 some farmers are supposed to undergo a change. Chess is a plant which has but a slight 

 relationship to wheat, and yet the question has been discussed for years, and many intelligent 

 men in other matters have strenuously maintained that wheat changes to chess ; the change 

 of course must be by a single leap, in a single season — a complete somerset, a perfect de- 

 gradation of the species in a single period of growth. When and where does the change 

 begin t The point which troubles farmers, is the appearance of chess where they have sown 

 wheat, and clean wheat too. But it is also notorious to every observer that nature too has 

 sown her seeds broad-cast, and that where there is land in a condition for seeds to germinate, 

 there they will spring up ; and it comes to pass from a wise provision, the tenacity of seeds 

 for the vital principle ;* and chess, while fond of a good soil, springs up by the side of fences 

 and fields, and scatters its seeds, which lie in the soil till favorable opportunities occur for their 

 germination. The fact that chess grows where wheat is expected is a trifling fact which is 

 easily accounted for, on known principles, while the transformation of one species of plant into 

 another is contrary to the laws which govern the growth and development of organized bodies. 



• The phrase, vital principle, is used for convenience ; it is not designed by it to express an opinion in regard to 

 the independent existence of something which presides over the movements of living being. 



