66 THE SALTON SEA. 



BACTERIA. 



Something remains to be said about the bacteria in these brines. As already pointed 

 out, decay goes on in them as in other waters ; but the bodies of the pecuHar organisms 

 inhabiting these concentrated and heavy solutions are decomposed, after death, by organ- 

 isms quite other than those carrying on similar decompositions in ordinary waters and in 

 the organisms adjusted to them. This is proved by the escape of plate and other cultures, 

 even when uncovered, from the usual infections from air and contact. But I have made 

 no attempt to isolate the species and determine the characteristic activities of the different 

 bacteria in these brines, except to ascertain, as previously stated (pp. 52-53) , that the red color 

 of these brines is the product of a very short and small bacillus (3.2 to 3.3m wide by 3.4 to 

 3.6m long) . Like the unicellular alga; inhabiting these brines, this organism can be cultivated 

 on agar-agar impregnated with brines of suitably high concentration. On agar-agar plates it 

 forms raised colonies ranging in shade from pink through clear red to crimson, according to 

 the size of the colony. The colonies first appear as small red spots, as indicated by figure 

 B, Plate 10. This is a photograph of an agar-agar plate, originally 1.190 specific gravity, 

 inoculated with a loopful from a very concentrated pink brine in a stock bottle. The inoc- 

 ulation was accomplished by drawing this platinum loopful lightly and rapidly across the 

 smooth surface of the plate in the shape of a Y ; for I hoped, by so doing, to accomplish the 

 same end attained in bacteriological laboratories by "pouring a plate," namely, the separa- 

 tion and distribution of the individuals over the surface of the plate. I could not "pour 

 a plate" in working with these organisms, for the temperature at which these brine plates 

 melt is fatal to the brine organisms, as experience had proved. Colonies of the Dunaliellas 

 formed along the line of inoculation, but I did not see this red colony until salt began to 

 crystallize out. It continued to grow for some time, but was finally lost in the snowy 

 mass of crystals which covered the plate as evaporation continued. 



A much larger and more diffuse growth is shown in figure a, Plate 10, in which another 

 plate is represented. This plate was thicker (deeper) and did not dry out so rapidly. It 

 was inoculated in a manner similar to b, but in two lines crossing each other, as in x. From 

 these plates other plates and a certain number of test-tubes of agar-agar brine were inocu- 

 lated. The two types of growth, colonial and diffuse, are shown in the figures of Plate 11. 

 In all of them the pigment diffuses more or less through the agar-agar, imparting to it a fine 

 and delicate shade of pink, which, with the glistening snowy crystals of common salt, give 

 a very striking appearance to the cultures. 



Suspecting that this small bacillus might be the cause of the red color which sometimes 

 develops in salt codfish, I determined to try two experiments: (1) to inoculate sterilized 

 salt codfish from one of my pure cultures of this pink organism; (2) to inoculate a sterilized 

 agar-agar brine plate from a piece of salt codfish which had turned red. I was fortunate 

 enough to find a box of "Georges Codfish" in which the fish was spotted with red. By 

 means of a sterile platinum needle I inoculated various sterile agar-agar brine plates from 

 the red spots. Presently colonies appeared on the agar-agar plates of the more concen- 

 trated brines, none forming on the more dilute brines. Growth on the agar-agar plates was 

 never very rapid, for laboratory air is rarely at the optimum humidity for this organism, 

 and the usual incubating temperatures are too high. 



The reverse of this experiment, inoculating sterilized salt codfish from my pure cultures 

 on agar-agar brine, was equally but not uniformly successful. It is obvious that if, in con- 

 travention of the regulations of the pure food and drugs act, an antiseptic or other deterrent 

 of growth be contained in the salt fish, attempts at inoculation would probably fail. I have 

 regularly failed with certain lots of fish at local groceries, and as regularly succeeded with 

 other lots bought at the same shops. One such culture on a piece of steam-sterilized cod- 

 fish inoculated from one of my pure cultures is shown in figure e, Plate 11. This culture is 

 several months old and shows the condition which salt codfish may and sometimes does 

 reach in the grocery or in the larder when kept where the air is moist and cool. 



