xli 

 February 20, 1871. 



The President in the chair. 



Eleven members present. 



The Committee on Publication reported, through their chair- 

 man, that there was not a sutficient number of papers in their 

 hands to make a new nujnber of the Transactions. 



Books were donated as follows : 



By Mr. Aug. Steitz, "Mining Statistics West of the Rocky 

 Mountains for 1870." 



By Mr. C. V. Riley, " The American Entomologist," Vols. I. 

 and II., and "Annual Report on the Noxious, Beneficial and 

 other Insects of the State of Missouri." 



By Mr. Bailey, a Catalogue of the Public School Library, in- 

 cluding a Catalogue of the Library of the Academy of Science. 



Mr. Steitz exhibited some specimens of gold nuggets and 

 crystals from Montana. 



Mr. Richard Hayes read a paper on " Earthquakes, their 

 Causes and Periodicity," which was referred to the Committee 

 on Publication. 



Dr. Engelmann remarked that in nature many changes are 

 going on before our eyes, which are due to the growth of 

 innumerable microscopic fungi, though at one time ascribed 

 to chemical change. It was interesting to observe how the 

 knowledge of these facts had gradually increased during the 

 last thirty years, for, in the works of chemistry of forty 

 years ago, a body was described under the name oi ferment^ and 

 its chemical properties considered, and it was then looked upon 

 as an unaccountable and mysterious thing. They knew then that 

 beer when filtered would not ferment, but could not tell why. We 

 now know that it is because the fungus is kept out. Alcohol, or 

 freezing, also destroys the fungus and produces the same effect. 

 No fungus can grow in substances which do not contain nitrogen. 

 The raising of bread is not due to the fungus, but to the carbonic 

 acid produced by the fungus. These fungi are very minute vesi- 

 cular bodies, and their true botanical nature was only recently 

 discovered. He described the two modes of propagation, by bud 

 and by sexual organs. The yeast fungus is only known to prof>- 

 agate in the first manner. He stated that the fungi found in de- 

 caying organisms were the cause of the decay. 



