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THE AMERICAN BOTANIST 



been brought to light. One of the most surprising is found in 

 the case of certain white primroses. In these there have been 

 found two strains, one of which is dominant to primroses with 

 colored flowers when the two are bred together, while the other 

 strain is recessive to colored flowers. Though the two strains 

 are indistinguishable to the eye, they can be separated by 

 chemical tests. In all probability much of the phenomena of 

 flower color and its behavior wdien crossed with other colors 

 will ultimately be found to rest on a chemical basis. 



Organic Compounds in the Soil. — The practice of 

 agriculture has been carried on so long that one might hastily 

 conclude that its principles are well established, but the facts 

 are otherwise. Just at present, agricultural scientists are 

 divided into two hostile camps over the subject of manures. 

 One side holds that the soil is inexhaustible and that the only 

 function of fertilizers is to enable plants to rid themselves of 

 toxic substances in the soil which are largely of their own 

 excretion. The other side insists that soils are easily worn 

 out or depleted of certain elements and that manures are nec- 

 essary to return these elements to the land. One result of the 

 controversy has been to set a good many chemists to studying 

 the soil more carefully and they are obtaining some very inter- 

 esting results. One line of w^ork has to do with organic sub- 

 stances in the soil, and of these upwards of twenty have already 

 been isolated. Judging from the names of some of them, the 

 soil is "fearfully and wonderfully made." We expect none 

 but the chemist to understand what they all mean but we give 

 the list for the benefit of the curious : cytosine, xanthine, hypo- 

 xanthine, adenine, histidine, arg"enine, choline, creatinine, hen- 

 triacontane, resin, resin acids, resin esters, pentose, pentosan, 

 phytosterol, agrosterol, gh^cerides, and nucleric, carboxylic, 

 parafinic, lignoceric, agroceric, dihydrosteric and monohydro- 

 stearic acids. In view of this list we may be pardoned for 

 thinking that those who claim that there are toxic substances in 

 the soil have a little the best of the argument. 



