220 president's address. 



We must first unravel the mystery of protoplasmic structure 

 before we can venture to claim tliat we have found an analogue 

 to the simplest movement it exhibits. 



I need hardly say that irritability, power of nutrition, and 

 cyclic changes, with power to multiply its kind — the essential 

 features of the simplest living cell of protoplasm — are not even 

 suggested as properties of these most interesting foams. 



A subject that must command, from a society like this, quite 

 as large an interest as the above, is the demonstration now 

 held to be completely established that it is to bacterias — pecies 

 of " micro-organisms " — that some of the most obscure and 

 important phenomena in agriculture are due. 



In the early part of 1891 M. Pasteur published some most 

 interesting results obtained by Herr Winogradsky by experi- 

 menting with soil taken from all quarters of the world,* 

 enabling him to conclude that two organisms are emjDloyed in 

 the nitrification of the soil, by which plants obtain their nitro- 

 gen. He had previously shown f that the nitrifying process 

 was effected by a single species of bacteria which was called 

 Nitromonas, but later he satisfied himself that there are 

 important morphological differences in these organisms, and 

 they were classed in a group of nitro-bacteria, the common 

 characteristic of which is the oxidation of ammoniacal nitrogen. 

 He now concludes that two organisms are employed in natural 

 nitrification, one forming nitrite and the other nitrate, and con- 

 sequently the process is completed in two periods. Both these 

 organisms he succeeded in isolating, the nitrate-former, whicb 

 is oval, about 0"5 of a micron long, and about two times less in 

 breadth ; the nitrite-forming organisms are oval or globular 

 and about double the size of those which form nitrates. 



In normal earth, nitrate only is formed, the production of 

 nitrous acid being a transitory phenomenon, and, even in the 

 presence of considerable quantities of ammonia, being oxidized 

 as soon as formed. The nitrite ferment, either under natural 

 or under artificial conditions, can only form nitrite, and nitrous 

 acid thus formed remains as such in the ground if the 7iitrate- 

 former be absent. 



If the nitrate ferment as well as the nitrite, however, be 

 added the process is completed in the ordinary way, only the 



* " Annalps de I'Institut Pastear," 1891, p. 577. 

 t Ibid,, \). ^2. 



