THE PHENOMENA OF LIFE. 1 {) 



pound, one of the most rapidly formed of which is starch. The first 

 step in the formation of starch is the union of carbon dioxide and water 

 to form formic aldehyde, COaH-HgO^CHaO-j-C^, oxygen being evolved; 

 then by polymerization the formation of sugar thus, 6 CIIgO^CeHiaOe; 

 and by dehydration, C 6 Hi 2 06 H 2 = C 6 Hio05, the production of starch. 

 In this way is starch synthesized or built up. Vegetable protoplasm by 

 the aid of its chlorophyll is able to build up a large number of bodies 

 besides starch, the most interesting and important being proteid or 

 albumin. It appears to be a fact that .the power which bodies possess 

 of being able to synthesize is to a large extent dependent upon the chlo- 

 rophyll they contain. Thus the power is only present to any marked 

 extent in the plants in which chlorophyll is found and is absent in those 

 which do not possess it ; while on the other hand it is present in the 

 extremely few animals which contain it and is absent except in certain 

 rare instances as one of the properties of animal protoplasm. 



It must be recollected, however, that chlorophyll without the aid of 

 the light of the sun can do nothing in the way of building up substances, 

 and a plant containing chlorophyll when placed in the dark, as long as 

 it lives, and that is not as a rule long, acts as though it did not contain 

 any of that substance. It is an interesting fact that certain of the bac- 

 teria have the chlorophyll replaced by a similar pigment which is able 

 to decompose carbon dioxide gas. 



Animal cells, except in the very rare cases above alluded to, do not 

 possess the power of building up from simple materials; their activity 

 is chiefly exercised in the opposite direction, viz., they have brought to 

 them as food the complicated compounds produced by the vegetable 

 kingdom, and with them they are able 'to perform their functions, set- 

 ting free energy in the direction of heat, motion, and electricity, and at 

 the same time eliminating such bodies as carbon dioxide and water, and 

 producing other bodies, many of which contain nitrogen, but which are 

 derived from decomposition, and only in very rare cases from building 

 up. 



It must be distinctly understood, however, that there are instances 

 of animal cells performing synthetic functions and of combining two 

 simpler compounds to produce one more complex, and it is quite possi- 

 ble that many of the processes performed by the cells of certain organs 

 are instances of synthesis, and not as they have been described of break- 

 ing down; and the reverse is undoubtedly the case with vegetable cells, 

 so that it is impossible to generalize to a greater extent than to say that 

 the tendency of the activity of the vegetable cell is chiefly toward syn- 

 thesis, and of the animal cell toward analysis. 



With reference to the substance chlorophyll it is necessary to say a 

 few words. It has been noted that the synthetical operations of vege- 



