The Organism and its Chemistry 87 



responding to the high development of the olfactory sense 

 there is a great diversity of odoriferous substances produced 

 by these animals. Something of the extent of this diver- 

 sification is indicated by Wheeler, the foremost student of 

 ants in this country, who remarks : "Kven the degenerate 

 human olfactories can detect the different species and in 

 some cases even the different castes of ants (Eciton) by their 

 odors." ^^ 



Among plants there are many examples of easily recog- 

 nizable differences in smell and taste between species of the 

 same genus and even between varieties of the same species. 

 In some species of Rhus, for example R. integrifolia, the 

 ripe fruit is covered with a thick, white, pasty exudate 

 which is extremely sour, while the fruit of R. laurina has 

 no trace of such a product. Since these species are both 

 native of southern California and often occur together, they 

 furnish an impressive instance of difference in chemical ac- 

 tivity of two closely related plants. While referring to 

 RhuSy the familiar fact that some of the species as Rhus 

 lobata "Poison-oak" produce an exceedingly active poison 

 while others do not, may be noted as a case of undoubted 

 chemical difference between species that are close of kin. 

 And this difference in the poison producing habit of plants 

 is rather common and found in widely separated portions of 

 the plant world. The cases of Rhus and Solarium, some 

 species of which are poisonous and some are not, chosen 

 from the higher plants, are paralleled bj^ the genus Amanita 

 (mushrooms) among lower plants. According to Charles 

 Mcllvaine, of the twenty-seven species of the genus, nine are 

 edible, nine are known to be either deadly or are so closely 

 allied to deadly species that it is unsafe to class them as 

 other than poisonous ; while about the others nothing Is 

 known in this regard. 



Some tests on apples make it highly probable that tlie 

 different kinds might be distinguished from one another to 



