282 THE AMERICAN MONTHLY [Deceruber, 



some way dependent upon their albuminoid constituents. It would 

 furthermore appear that this singular and apparently most significant 

 capacity of the body fluids is ultimately associated with that complex 

 condition which we call life. 



The paper is a most excellent summary of the present condition of 

 this question, ^ well as a record of his own personal experience. — 

 {Afedlcal I^eco7'd^ J^ri. 25, 1890.) 



Bacteria in Milk. — Professor H. W. Conn, in discussing the bac- 

 teria of milk, remarks that their function varies with the species, some 

 of them having the property of imparting an agreeable flavor to the 

 butter made from it, while others communicate a disagreeable odor and 

 taste. 



From milk and cream the author has isolated forty different species, 

 which, from their effect, are divisible into three classes : (i) some pro- 

 duce no visible effect, the milk remaining apparently unchanged. 

 Some of these, however, render it slightly acid, others slightly alkaline, 

 and nearly all produce certain decomposition odors ; (2) another series 

 has the power of breaking up the milk-sugar, producing sufficient acid 

 to curdle the milk. To this belongs B. acidi lactici ; (3) a third class 

 curdles milk, but the reaction is either alkaline or the reaction is not 

 affected. Such bacteria have the additional function of dissolving the 

 curd which they produce, converting it slowly into peptones, whereby 

 the milk becomes liquid again. 



The author then proceeds to discuss the connection between butter 

 and bacteria, the connection being established through cream, in which 

 the growth is longer continued and more prolific. How the action of 

 bacteria on cream results in what is known as " ripening," by which 

 butter "comes" more easily; secondly, it keeps longer; thirdly, the 

 flavor is improved. The ripening is effected by the action of bacteria, 

 which disintegrates the albumen, partly by production of an acid and 

 partly by a peptonization. The flavor is due to the impregnation of 

 the butter with aromatic principles, the product of decomposition ; the 

 diflerence in taste and odor being due to the action of different bacte- 

 rial ferments. Hence butter made from sweet cream is flat, insipid, 

 and tasteless, because the bacteria have not had time or opportunity to 

 produce the volatile decomposition products. The author finally dis- 

 cusses the relation of milk-souring to electricity. From a series of 

 experiments made on milk, he finds that electricity has not this effect 

 on milk, and offers in explanation that "thunderstorms" are usually 

 preceded by climatic conditions of temperature and moisture very favor- 

 able to bacteria growth. (Associated Dairying Comr., Board of Agri- 

 culture Report for 1S90.) 



BIOLOGICAL NOTES. 



By prof. J. H. PILLSBURY, 



NORTHAMPTON, MASS. 



Vitality of Vegetal Tissue. — A neighbor brought us, early in the 

 season, a section of a woodbine {Ampelopsis qi^mquefolia) stem which 

 was broken from the vine some time during the summer of 1889, prob- 

 ably in August, a considerable portion of which was still fresh and 



