SEVENTEENTH ANNUAL MEETING. 261 



caused by the presence in the yeast of aberrant forms which were not active 

 alcoholic ferments, and their domiuant influence interfered with the desired 

 fermentation process. From the results of his experiments he was enabled to 

 point out a method of obtaining pure yeast, which was found to be an efficient 

 remedy for the faulty fermentations which had prevailed under the old system. 



This led to the establishment of a new industry of breeding pure veast to 

 supply the wants of the brewers and wine makers. 



The microscopic forms of life we have under consideration have been popu- 

 larly called "bacteria," but as this term is properly applied to the members of 

 a particular genus only, the word microbe is coming into use as a general term 

 to designate an individual of any of the allied groups in which the genus 

 bacterium is included. 



[The classification of microbes, and the general form of the leading genera 

 and species highly magnified and drawn to the same scale, were illustrated 

 by diagrams.] 



Are these minute beings plants or animals, or do they properly belong to a 

 separate kingdom of nature P 



The fundamental differences which distinguish plants from animals are to 

 be found in their processes of nutrition. It is a matter of common observation 

 that animals are dependent upon plants for their food, and that plants obtain 

 their nutritive materials from the soil and the atmosphere. Stated in more 

 definite terms, plants take their nitrogen and oxygen from the soil, and their 

 carbon from the atmosphere; while animals, on the other hand, can only 

 appropriate carbon and nitrogen from the complex compounds of organic mat- 

 ter, and their princpal supply of oxygen is obtained from the air. Plants use 

 as food comparatively simple compounds, as carbonic acid, water and nitric 

 acid, while animals require food of more complex and unstable chemical com- 

 position, that has been elaborated by living organisms. 



Now microbes seem to combine the nutritive processes of both plants and 

 animals. They can obtain their supply of carbon and nitrogen from either 

 organic or inorganic materials, and while some, under certain conditions, prefer 

 to take their oxygen from the air, others readily obtain it from organic and 

 inorganic substances. They can make use of simple binary compounds, or of 

 those of the most complex composition. In their nutritive processes they are, 

 therefore, unlike plants, and differ from animals, while they combine the 

 methods of both in the general performance of the function. 



Moreover, recent experiments have shown that, as animals depend on plants 

 to prepare their food for them, so plants, in their turn, are equally dependent 

 on microbes in the soil to elaborate their food supplies derived from either 

 organic or inorganic materials. 



We have life, therefore, manifested on three distinct planes; the lower occu- 

 pied by microbes that are essential to the well-being of plants on the plane 

 above them ; while animals on the highest plane can only exist at the expense 

 of the plane of plant life beneath them. It seems probable, however, that 

 animals, as well as plants, are directly dependent upon the lower plane of 

 microbe life for their existence. 



Plants have been called the " hewers of wood and drawers of water " for 

 the animal kingdom, but microbes seem to perform the same menial labor for 

 both of the two kingdoms of nature above them. 



The latest physiological discoveries seem to indicate that the function of 

 nutrition consists largely in the transfer and storage of energy, and we must 



