44 BIOLOGY OF THE PROTOZOA 



uncertain and experimental stage. Beyond somewhat glaring gen- 

 eralizations of chemical groups as listed above, we know but little 

 that is definite concerning the chemistry of living matter. It is 

 freely admitted by those who are in the best position to know, 

 that many highly labile substances of active protoplasm are de- 

 stroyed or changed beyond recognition by the processes of modern 

 chemistry. Some of these are probably quite unaccounted for; 

 another group can be identified as chemically definable substances 

 which, however, we can only assume to be an integral and neces- 

 sary part of the protoplasmic make-up. Many qualitatively impor- 

 tant bodies are overlooked or hidden from observation; others are 

 materials in an absorbed condition or so enmeshed among the 

 colloidal stuffs that their clear demonstration is as yet scarcely 

 possible. The unavoidable destruction, physically and chemically, 

 of protoplasm during analysis must bring about mixtures, or chemi- 

 cal and physical changes amongst the substances originally present, 

 hence the position of different stuffs cannot be definitely ascertained 

 as fundamental or derived until methods are more refined and more 

 exact. 



With the exception of the Mycetozoa which have been used 

 extensively for the purpose of protoplasmic analysis, protozoan 

 protoplasm, owing to the minute size of the individuals, has been 

 very little studied in connection with the chemistry of protoplasm, 

 and our present knowledge concerning it is based mainly on morpho- 

 logical considerations together with the results of chemical analysis 

 of protoplasm in higher types of animals and plants. 1 



The granules which invariably appear in protoplasm, and which 

 are probably intimately connected with the varied activities going 

 on during life are different in their chemical make-up although, 

 morphologically, they appear much the same. This is shown by 

 their reactions to micro-chemical tests of different kinds and it is 

 not unreasonable to infer that the specificity of protoplasm in dif- 

 ferent species of Protozoa is due in large part to the chemical and 

 physical composition of these granules and to interactions going on 

 amongst them. 



The almost infinite variety of form and structure represented by 



1 An example of one concrete case of chemical analysis may be cited. This is not 

 accepted without question, but it indicates the nature of the substances which enter 

 into the make up of protoplasm — in this case of the Plasmodium of the mycetozoon, 

 Fuligo varians, as analyzed by Lepeschkin (1923, 1926). 



Per cent. Per cent. 



Monosaccharid . . . . 14.2 Globulin 0.5 



Albumin 2.2 Lipoproteid 4.8 



Amino-acids ) Neutral fat 6.8 



Purin bases > . . . . 24 . 3 Phytostearin 3.2 



Asparagin J Phosphatids 1.3 



Nucleoproteid 32 . 3 Other organic stuffs . . . 3.5 



Free nucleic acid . . . . 2.5 Mineral stuffs 3.4 



