PHYSIOLOGICAL CHANGES. 135 



These, however, certainly cannot be classed as exact experi- 

 ments. Yet so far as they have scientific value, it is undoubtedly 

 in the direction of the maintenance of the proposition that the 

 nature of organisms may be profoundly changed by tempo- 

 rarily changing the media in which they are grown ; for it is on 

 this basis that we must account for changes in results. Such 

 a proposition will, however, require the most rigid proof be- 

 fore we can accept it as a modification of the essential nature 

 of the products, that will be carried, with the organism, back 

 into the media froui which it was transplanted. 



The other proposition, that the products of the organism 

 change with the media in which it is grown, is of a very 

 different nature, and much more plausible. We all know 

 that our own urine may be changed from acid to alkaline, 

 by certain changes in diet; that the amount, and to some 

 extent, the quality of opium, is affected by the nature of the 

 soil in which the plants are grown. Still it does not appear 

 in these cases that the essential features of the waste products 

 are more than modified in some unimportant particulars. 

 The urine will still furnish urea, and the opium will still 

 furnish morphine, although each will, possibly, furnish their 

 characteristic product in diminished quantity. But in either 

 case, the original character of the product will be resumed 

 with the resumption of the original diet. 



One would scarcely expect the yeast plant to produce a 

 nitrogenous alkaloid when grown in a pure solution of sugar 

 or starch, containing none of the element nitrogen. So an 

 organism whose normal habitat is nitrogenous compounds, 

 and whose waste products are nitrogenous, if transferred and 

 found to grow in pure starch, would certainly not produce a 

 nitrogenous alkaloid as a part of its waste product, while 

 growing in the starch; yet I would expect it to again produce 

 the nitrogenous product if replaced into nitrogenous matter ; 



