192 PHYSIOLOGY OF MICROORGANISMS 



results from the ether and alcoholic extracts in terms of per cent, of 

 dry substance. Nageli and Loew H found 5 per cent, in a bottom- 

 fermentation beer yeast. The Bact. tuberculosis has always occupied 

 a conspicuous place on account of its fat-content. Klebsf estimated 

 20.5 per cent, of a red fat and 1.14 per cent, of a white fat. In amoebae, 

 fat globules are frequently detectable in very large numbers. 



Apparently the fatty materials found in different organisms are of 

 diverse natures. Hammerschlag | believed most of the fatty substances 

 of Bact. tuberculosis consist of tripalmitin and tristearin. De Schweinitz 

 and Dorset || obtained palmitic and arachidic acids. Bandraus recog- 

 nizes stearin and olein together with the lipoids, cholesterin and lecithin, 

 in the same species. It is a matter of determination that stearin, 

 palmitin, cholesterin, lecithin have also been recognized in molds, 

 yeasts, and protozoa. There is no characteristic uniformity existing 

 between species other than certain fatty substances are more commonly 

 met with in some than others. In the same species the fat content or 

 amount is subject to wide variations. It was noticed by Meyer If that 

 in B. tumescens there was an increase of fat till spore production when 

 the fat completely disappeared. There was no fat in the spores. 



The Ash Elements. It is exceedingly difficult at the present time to 

 determine the number, kinds and limitations of inorganic elements 

 included in the compositional structure of protoplasm. Both qualita- 

 tive and quantitative studies fail in solving the values and relationships 

 of these elements in vital processes. From the nutritional viewpoint 

 certain elements may be recognized as very important and others as 

 incidental. Uniformity, however, exists only within certain bounda- 

 ries, if it exists at all. The elements which stand out most con- 

 spicuously are phosphorus, potassium, sodium, calcium, sulphur, 

 magnesium, iron, silicon, but manganese, aluminum, copper and others 

 have been recognized at times. 



The finding of an element does not establish its relation to proto- 

 plasmic synthesis. Attempts have been made to substitute other 

 elements for those considered essential but such efforts cannot be 



Nageli and Loew, Sitzgsber. d. Kgl. Academie d. wiss. in Munchen, 1878. 

 tKlebs, Cent. f. Bakteriologie, XX, 488, 1896. 

 tHainiiu isc hlag, Monats f. Chem., X, 9, 1899; Cent. f. Klin. Med., XII, 9, 1891. 



Srhwcinitz and Dorset, Jour. Amer. Chem. Soc., XVII, 605, 1895; XVIII, 449, 1896 

 XIX, 782, 1897; XX, 618, 1898. 



13andraus, Compt. rend. ac. sc., 142, 657, 1906. 

 IfMeyer: Flora, 432, 1889. 



