64 DE. BASTIAN ON THE 



potato, or to show that they are not heterogenetic products. 

 Tet their customary absence from the tissues of such, vegetables 

 under ordinary conditions, and their presence when these are 

 placed under certain unnatural conditions (which of themselves 

 by no means favour contamination), makes this seem a not unrea- 

 sonable explanation of their presence. I merely call attention to 

 these points now, witbout venturing to express any opinion of my 

 own, as they are parts of the subject to which, as yet, I have given 

 little attention. 



Then, in regard to the extension of M. Pasteur's doctrine in 

 1876, and the confirmation by him of the fact discovered by M. 

 Musculus that fermenting urine contains a soluble chemical fer- 

 ment separable from and capable of inducing in urine precisely the 

 same sets of changes as ferment-organisms produce therein, several 

 questions of much interest arise, which have as yet received sur- 

 prisingly little attention. 



Grranting that this newly discovered chemical ferment is, as M. 

 Pasteur declares, a product of the life-activity of ordinary ferment- 

 organisms, we want to know («) what the effect would be of in- 

 troducing some of this separated cbemical ferment into sterilized 

 urine, and whether, as a result of its action the ordinary ferment- 

 organisms ever appear in the fluid. We also want to know (b) 

 what exact degree of heat this chemical ferment is capable of un- 

 dergoing without losing its activity, — whether, in fact, it is decom- 

 posed at temperatures bigber or lower than those sufficing to kill 

 or arrest the activity of the living ferment-organisms by which it 

 has been produced. "We ought to know (c) how it is affected by 

 desiccation and, if minutely " particulate," like Dr. Sanderson's 

 pyrogen *, wbetber such desiccation will subsequently enable it 

 to resist a higher degree of heat in fluids than it could previously 

 withstand. And lastly (d) we want to know how many different 

 kinds of chemical ferments may be found in urine under different 

 conditions, whether similar ferments are engendered during the 

 course of many other fermentations, and whether they are gene- 

 rally like pyrogen particulate in nature, or soluble, as zymase (the 

 " ferment inversive " of Berthelot) is reputed to be. 



Such not-living chemical principles resulting from the life- 

 activity of independent ferment-organisms seem altogether 

 analogous to those longer known chemical ferments of the animal 

 body and of the plant, which are capable of exciting analogous 

 * Brit. Med. Journ.. Feb. 13, 1875, p. 201. 



