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SCIENCE 



[N. S. Vol. XXXIII. No. 851 



egg does not swell enormously after oviposi- 

 tion, it is improbable tbat the fall in osmotic 

 pressure is due to the absorption of water. 

 The simplest explanation is that the egg is, at 

 this time, permeable to the internal osmotic 

 substances. That this permeability is only a 

 temporary condition is indicated by the fact 

 that the osmotic pressure of the resulting 

 embryo rises until it reaches that of frog's 

 serum. 



In conclusion, I wish to thank the Carnegie 

 Institution, and especially Dr. Chas. B. Daven- 

 port, the director of the laboratory. 



J. F. McClendon 

 Station for Experimental Evolution, 

 Cold Spring Harbor, 

 Long Island, N. Y., 

 April 3, 1911 



THE bacteriology of " TATTE MELK " 



This milk is a favorite food article in Nor- 

 way and Sweden and is prepared by inocu- 

 lating sweet cow's milk with leaves of Pin- 

 guicula vulgaris or with a small amount of the 

 finished product. Sometimes pieces of linen 

 are dipped into the fermented milk, allowed to 

 dry, and used for inoculation. This method 

 makes it feasible to send the material by mail. 

 The milk is thick and slightly stringy and has 

 a slight cheesy taste and odor. 



I obtained three samples of the milk and 

 one of the impregnated linen from a reliable 

 source for the purpose of determining the ac- 

 tive agents in it. A microscopic examination 

 of the samples showed streptococci in large 

 numbers, mostly in diplococcus form, but fre- 

 quently in chains of ten to sixteen members. 

 Two species of yeasts were also in abundance, 

 one being an oval yeast, the other a large 

 organism with square ends, often forming 

 long filaments. Besides these organisms there 

 were present some bacilli resembling B. coK 

 in shape and size, which proved to be gram- 

 negative. There were also a few large bacilli 

 resembling that group of bacilli, which is 

 found in milk almost invariably and forms 

 larger amounts of acid than ordinary lactic 

 acid bacteria. Microscopic examination of 

 the impregnated linen did not show yeast cells. 



Plates were prepared from the four samples 

 in dextrose-litmus-agar and in beerwort agar; 

 litmus milk was inoculated with the original 

 material. The milk, when intended for con- 

 sumption, is inoculated at body temperature, 

 and therefore all plates and cultures were in- 

 cubated at 37° C. 



There was no difficulty in isolating the dif- 

 ferent organisms from the plates. The 

 streptococcus could not be distinguished 

 microscopically from 8. lacticus, but its ac- 

 tion on sterile milk differed in that it coagu- 

 lated but slowly; after coagulation the 

 coagulum was stringy, similar to the coag- 

 ulum formed by B. hulgaricus, but in a 

 smaller degree. The oval yeast gave the 

 microscopic picture of Saccharomyces cerevi- 

 siae. It ferments lactose and saccharose with 

 violent gas production, levulose slowly, and 

 maltose not at all. Cultures of this yeast in 

 liquid beerwort impart a somewhat stringy 

 consistency to the medium. The other yeast 

 proved to be O'idium lactis, which is always 

 present in milk and in this milk is probably 

 responsible for a slight cheesy taste and odor. 



Cultures of the samples were also made in 

 broth with the addition of 2 per cent, dex- 

 trose and 0.5 per cent, acetic acid. The pres- 

 ence of the acid restrains most bacteria, so 

 that those forming a large amount of acid can 

 be detected by this method. Dextrose also 

 favors the growth of these bacilli. After 

 twenty-four hours' incubation they were found 

 in abundance in the cultures. These organ- 

 isms, however, do not multiply readily in 

 milk in competition with other bacteria and I 

 do not believe that they have any bearing 

 upon the production of " Tatte Melk." In 

 fact sterilized milk, inoculated with strepto- 

 cocci, isolated from the samples, and with the 

 two species of yeasts, resembled the original 

 product closely after twenty-four hours. 

 Whether the yeast has anything to do with 

 the stringiness of the milk is doubtful, but it 

 adds to the palatability of the milk. It does 

 not produce nearly as much gas in the milk 

 as it does in pure culture. 



P. S. Heustemaun 



University or Chicago 



