32 H^EMATOCOCCUS LESS. 



matters being formed and finally got rid of. Obviously, 

 then, absorption of oxygen must take place, or in other 

 words, respiration must be one of the functions of the pro- 

 toplasm of Haematococcus as of that of Amoeba. In many 

 green, i.e., chlorophyll-containing, plants, this has been proved 

 to be the case ; respiration, i.e., the taking in of oxygen and 

 giving out of carbon dioxide, is constantly going on, but 

 during daylight is obscured by the converse process the 

 taking in of carbon dioxide for nutritive purposes and the 

 giving out of the oxygen liberated by its decomposition. In 

 darkness, when this latter process is in abeyance, the 

 occurrence of respiration is more readily ascertained. 



Owing to the constant decomposition, during sunlight, of 

 carbon dioxide, a larger volume of oxygen than of carbon 

 dioxide is evolved; and if an analysis were made of all 

 the ingesta of the organism (carbon dioxide plus mineral 

 salts plus respiratory oxygen) they would be found to con- 

 tain less oxygen than the egesta (oxygen from decomposition 

 of carbon dioxide plus water, excreted carbon dioxide and 

 nitrogenous waste) ; so that the nutritive process in Haema- 

 tococcus is, as a whole, a process of deoxidation. In 

 Amoeba, on the other hand, the ingesta (food plus respi- 

 ratory oxygen) contain more oxygen than the egesta (faeces 

 plus carbon dioxide, water, and nitrogenous excreta), the 

 nutritive process being therefore on the whole one of 

 oxidation. This difference is, speaking broadly, character- 

 istic of plants and animals generally; animals, as a rule, 

 take in more free oxygen than they give out, while green 

 plants always give out more than they take in. 



But destructive metabolism is manifested not only in the 

 formation of waste products, but in that of substances 

 simpler than protoplasm which remain an integral part of 

 the organism, viz., cellulose and starch. The cell-wall is 



