374 



SCIENCE. 



[N. S. Vol. XVII. No. 427. 



isms during the early part of the ripening 

 period. For this work peptone-litmus- 

 gelatin was used and the milk was plated 

 at intervals of three hours. From these 

 plates the total number of organisms, the 

 number of acid-producing bacteria and the 

 different species, as far as possible, were 

 determined. The results of a long series 

 of experiments seem to show that the de- 

 crease in numbers was due, not to any 

 'property or action' possessed by the milk, 

 but to the natural dropping out of certain 

 species of bacteria which do not find the 

 milk a suitable medium in which to grow. 

 Fresh milk obtained under ordinary con- 

 ditions contains a large variety of types 

 and species of bacteria, while milk which 

 has soured or curdled contains but few 

 species, often not more than two or three. 

 Fresh milk ordinarily contains but few of 

 the typical lactic organisms which later 

 cause souring and coagulation. When 

 these species have once gained access to 

 the milk their growth is constant and quite 

 uniform from the first. Certain other acid- 

 producing species, however, and many non- 

 acid species do not find the milk a favorable 

 medium in which to grow, and drop out. 

 Some species appear only in the plates 

 made from the fresh milk, while other spe- 

 cies may continue for a few hours and then 

 disappear. Usually the decrease in the 

 numbers of the miscellaneous species is 

 greater than the increase in the 'lactic' 

 species, during the first few hours, so that 

 plate cultures made when the milk is a 

 iew hours old will show smaller numbers 

 ■of bacteria than were found in the fresh 

 milk. - 



Nummary of the Steps which must he Fol- 

 lowed in Staining Flagella hy Loffler's 

 Method: W. R. Copeland, Bureau of 

 IPiltration, Philadelphia, Pa. 

 The films of bacteria on the cover slips 



should be made from suspensions of bac- 



teria obtained by immersing the cells in 

 water for one or two hours in order to 

 dissolve the outside gelatinous capsule. 



Loffler's mordant should be made of the 

 best grade of tannic acid with ferrous sul- 

 phate and Gruebler's basic fuchsin. This 

 mordant should be heated to 70° or 75° C, 

 until a stream of steam rises for a distance 

 of two inches. The preparation should 

 then be set aside for half a minute. The 

 stain is made of the best grade of ani- 

 line oil, absolute alcohol and a saturated 

 alcoholic solution of Gruebler's basic fuch- 

 sin. The stain should be applied cold, for 

 from eight to ten seconds. 



Finally Loffler's method of staining fla- 

 gella is better and more powerful than 

 either van Ermengem's, Pitfield's or L6- 

 witz's methods; It magnifies the size of 

 the cells and flagella in a manner that is 

 especially favorable for class demonstra- 

 tion. 



Egg Medium for the Cultivation of Tv^ 

 bercle Bacilli: M. Dorset, Biochemic 

 Laboratory, Washington, D. C. 

 A further report of the results obtained 

 by the use of this medium which had been 

 previously described in American Medi- 

 cine, April 5, 1902, and the 'Eighteenth 

 Annual Report of the Bureau of Animal 

 Industry,' 1901. 



Cultures were made from more than 

 seventy-five tuberculous rabbits and guinea- 

 pigs, with almost uniform success, the few 

 failures being traceable to a contamination 

 of the culture tubes or the presence of very 

 small numbers of tubercle bacilli in the 

 tissues from which the cultures were taken. 

 The medium seems to be specially well 

 adapted for obtaining the first growth of 

 tubercle bacilli from animals. Tubercle 

 bacilli of bovine origin gave a slightly less 

 abundant growth than the human tubercle 

 bacilli, and the gross appearances of the 

 cultures differed slightly. The morpho- 



