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connection, and either one or both receiving therefrom a positive 

 gain. The difficulty here seems to be that it is impossible to say 

 whether an injury is done to the plant or not. Prof. Schwen- 

 dener, in discussing the question, gave for an example the lichen. 

 Some botanists assert that the presence of the fungus, instead of 

 retarding the development of the alga enclosed, is 'conducive to 

 its growth and development. This statement, he claims, is not 

 substantiated by fact. Who can say that it is not an injury to 

 the alga that it has lost its power of sexual reproduction? It is 

 quite true that while it has lost in this way, it has gained in abil- 

 ity of vegetative propagation. It is a point which no scientist 

 has yet been able to determine, that is, to exactly balance the 

 gains and losses so that it is possible to say whether the alga 

 would have reached a higher stage of development had it not 

 been made use of by the fungus. Prof Schwendener summarily 

 disposes of this question by declaring that the word Symbiosis 

 may be applied to any combination of individuals for mutual 

 benefit. 



Another question, and one including a far wider range than 

 this, goes back practically to the old one, " do plants make use 

 of the free nitrogen of the air ?" 



This old question comes up in new forms, and like many other 

 old questions seems only to increase in difficulty as it increases in 

 age. 



In a certain form of this subject Frank also plays a very 

 prominent role as investigator. A word here in explanation of 

 the fact of so many subjects taken up him. 



He holds a prominent position in this agricultural college, and 

 the question of adaptation of crops to soil in Germany is one of 

 great practical importance. Therefore the authorities, or those in 

 charge of this institution, claim from the professors engaged in 

 it, a certain amount of work in practical directions. This has led 

 Prof. Frank to take up questions bearing decidedly on the 

 chemical side of plant physiology. As he is not himself a prac- 

 tical chemist, he employs one in his laboratory to make his most 

 important and finest chemical tests. 



In respect to the form in which this question is now being 

 worked over in Berlin, there is one branch of it which seems to 



