30 II/EMATOCOCCUS less. 



with a comparatively small number of atoms to the 

 molecule. 



The next step seems to be that the carbohydrate thus 

 formed unites with the ammonia salts or the nitrates absorbed 

 from the surrounding water, the result being the formation 

 of some comparatively simple nitrogenous compound, prob- 

 ably belonging to the class of amides, one of the best 

 known of which — asparagin — has the formula C4HgN^03. 

 Then further combinations take place, substances of greater 

 and greater complexity are produced, sulphur from the ab- 

 sorbed sulphates enters into combination, and proteids are 

 formed. From these, finally, fresh living protoplasm 

 arises. 



From the foregoing account, which only aims at giving 

 the very briefest outline of a subject as yet imperfectly un- 

 derstood, it will be seen that, as in Amoeba, the final result 

 of the nutritive process is the manufacture of protoplasm, 

 and that this result is attained by the formation of various 

 substances of increasing comi)lexity or anastates (see p. 18). 

 But it must be noted that the steps in this process of con- 

 structive metabolism are widely different in the two cases. 

 In Amoeba we start with living protoplasm — that of the prey 

 — which is killed and broken up into diffusible proteids, 

 these being afterwards rc-combined to form new molecules 

 of the living protoplasm of Amoeba. So that the food of 

 Amoeba is, to begin with, as complex as itself, and is first 

 broken down by digestion into simpler compounds, these 

 being afterwards re-combined into more complex ones. In 

 Hsematococcus, on the other hand, we start with extremely 

 simple compounds, such as carbon dioxide, water, nitrates, 

 sulphates, &c. Nothing which can be properly called diges- 

 tion, i.e., a breaking up and dissolving of the food, takes 

 place, but its various constituents are combined into sub- 



