in TWO CLASSES OF SPECIFIC CHARACTERS 143 



vation also diminishes its injurious properties in a 

 marked manner. Of course, these differences in the 

 physiological influence of the same plant can only be 

 ascribed to variations in the protoplasmic or physio- 

 logical processes of the plant, so that they afford 

 very good instances of physiological variation. These 

 are a few instances among many ; but they are enough. 

 We may then draw the inference that between 

 different species there are not only external dif- 

 ferences which may seem more or less unimportant 

 although we must believe them to have some use- 

 fulness there are also other differences of a physio- 

 logical nature. As yet we are acquainted with but 

 a few of them, the matter having been but very 

 slightly investigated, but we may rest assured that 

 in fact they are numerous, and often very consider- 

 able. While they may seem, and perhaps are, in 

 many circumstances of small importance, they may, 

 in others, become of the highest interest, and de- 

 termine life or death. This is the main fact I wish 

 to illustrate, and I entertain no doubt whatever 

 concerning the novel, and certainly startling, character 

 of the results, which will be put forward when some 

 competent physiologist and chemist shall have devoted 

 some time to the comparative investigation of two 

 species, or better of two varieties of the same species, 

 from this point of view. 



