ORIGIN OF LO WEST OR GA NISMS. 1 03 



will, on the contrary, pass through such changes when 

 pressure is removed, and the fluids are preserved 

 in vacno. It is not pretended that this is a rule appli- 

 cable to all organic fluids far from it. Diminution 

 of pressure does seem, however, to be a very potential 

 cause of change in some fluids. The extent to which 

 changes of a fermentative character can progress in 

 the absence of atmospheric oxygen, is also evidently 

 subject to much variation, in accordance with the 

 nature of the dissolved fermentable substances. 



These facts are not so new and exceptional, however, 

 as they may at first sight appear. It has been long 

 known that a boiled fluid extremely prone to change, 

 will not yield infusoria if the vessel in which it is 

 contained is filled with the fluid. Burdach says * :- 

 " Gruithuisen a reconnu que des infusions, meme tres 

 fecondes d'ailleurs, celles du foin par exemple, ne 

 donnaient point d'infusoires dans des flacons de 

 verre dont le bouchon etait assez enfonce pour toucher 

 a la surface de 1'eau." On the other hand, no experi- 

 ments with which I am acquainted, in which heated 

 fluids and calcined air have been shut up in closed 

 flasks, have yielded so many positive results as those 

 of Professor Wyman of Cambridge, U.S., and his 

 were performed under precisely the reverse conditions. 

 Large flasks were used, and only -^ Y V of their bulk 



*' Traite de Physiologic.' Translated by Jourdan. 1837. t. i., 

 p. 18. 



