188 TEANSACnONS OF THE HOETICULTUKAL 



We hope by further experiments to arrive at more definite con- 

 clusions on this point. 



As to the necessity for the presence of organisms, in order that 

 seeds may germinate, we have quite conclusively proved the con- 

 trary. Different seeds, it is true, behave quite differently, but in no 

 instance have we been unable to germinate seeds free from all organ- 

 isms. With the methods at first used for destroying the organisms, 

 even when applied in an exjtremely mild form, there was no growth 

 of seeds, and it did seem likely to be true that "no organisms" 

 meant "no germination.'" For example, seeds of cucumber, radish, 

 and peas were washed in a 1 per cent, solution of corrosive subli- 

 mate, and immediately rinsed with pure water and kept free from 

 contact with organisms. They persistently refused to grow. These 

 same kinds refused to grow when watered with a solution contain- 

 ing but 1 of the corrosive sublimate in 20,000 of water, that strength 

 being sufficient to keep out all bacteria. However, under these 

 conditions, some kinds, as corn, would grow. So we could not be 

 sure yet but that our mild disinfectants had also killed the seeds. In 

 the same way, seeds that were allowed to remain forty-eight hours in 

 an atmosphere of 1 part of chlorine gas to 100 parts of air, were en- 

 tirely out of the notion of growing, corn alone excepted. But, 

 finally, this test was made: A bottle Jj full of pure distilled water 

 was filled, the remaining | with chlorine gas, and thoroughly shaken 

 until the water has dissolved about 8-10,000 of its own weight of the 

 gas. This was made further into samples of various strengths, all 

 of which were quite sufficient to prevent the growth of micro-organ- 

 isms. 



Up to a certain limit, that of about 1 to 1,500, all seeds, so far 

 as tested, would germinate with great readiness, being in all cases 

 stimulated rather than retarded by the treatment. 



Now, what is the sum of the matter so far? 



1st. That seeds are not dependent on the presence of micro- 

 organisms for germination. 



2d. That growing plants are dependent upon the presence of 

 certain forms of micro-organisms, if not in some immediate and vital 

 connection, then surely as the constant means whereby there is sup- 

 plied the nitrates for plant food, and without which the plant could 

 not live. 



And now that we understand the conditions most favorable to 

 the growth of organisms, we may draw some conclusions as to what 

 method will produce in soils the greatest amount of this chiefest of 

 plant foods — nitrates. The whole matter is very suggestive of prac- 

 tical hints, and will doubtless prove, in time, of real, every-day value. 

 The conditions most favorable to nitrification are, briefly: Heat, 

 about 85°, with a limit of from 55° or 60° to 95° or 100°. The 

 presence of a salifiable base, as calcium or potassium. Moisture is 

 essential: darkness, seemingly; and in the soil, nitrification is most 

 abundant in the first two or three inches. 



