804 JOURNAL OF FORESTRY 



respiration of plants is no different from tliat of animals. So far as is- 

 known, roots do not possess stomata. 



Another author writes thus of the process of transpiration: 



"The process of taking up minerals in solution through the roots, of deposit- 

 ing these minerals, and giving off water from the leaves is called transpiration."' 



Transpiration, a passive and unavoidable danger, rather than a func- 

 tion of plants, is usually defined as the evaporation of water from the- 

 aerial parts of the plant and certainly does not include the other phe- 

 nomena the author speaks of. 



A third author writes : 



"The leaves are the stomachs of the tree, to which the thin, watery solutions 

 are carried." 



This is practically the same analog}' made by the first author cited. 

 It is a poor one for several reasons. The feeding processes of plants 

 and animals are not at all alike. The animal eats food already prepared, 

 which is digested by the stomach, for the most part. For the reason 

 already spoken of, the leaf cannot be considered analogous to the 

 stomach of animals. There is also another reason. The plant must 

 make its own food out of food materials, and this is done in the leaves;, 

 the leaves are therefore more a laboratory for manufacturing food 

 than a particular place where food is digested. The same author also 

 confuses the two processes of transpiration and photosynthesis, thus: 



"In addition to the transpiration process which results in the giving off 

 of oxygen and water vapor, the tree breathes like any other living organism; 

 that is, it takes in oxygen and emits carbon dioxide." 



Transpiration, as already pointed out, has nothing to do with the 

 phenomenon of giving off oxygen. Oxygen is a by-product of photo- 

 synthesis and not of transpiration. It appears that carbonic acid 

 (OH. COOH) is by some means reduced to formic acid (H. COOH) 

 and later to the simplest carbohydrate, formaldehyde (H. COH). In^ 

 the course of this reduction a molecule of oxygen is set free. 



The fourth author, speaking of the leaves, writes : 



"The latter serve as the stomach and lungs at the same time. The soluble 

 salts coming in through the delicate cell walls of the root hairs pass up through 

 the sapwood to the leaves. There the water is combined with oxygen, and car- 

 bon dioxide found in the air is taken in through the openings, 'stomata,' found 

 on the under side of the leaves. These two ingredients are combined in the 

 presence of a green substance called chlorophjdl, found in the leaf cells, to make 

 starch and sugar." 



