No.502] CHEMICAL MECHANICS IN LIVING PLANT 647 



supplies for an internal process have to be obtained from 

 outside, then we have the complications of absorption and 

 translocation to obscure the issue, especially in the case 

 of a higher plant. 



Let us first take a case where the carbohydrate supply 

 is in excess and the amount of catalytic protoplasm is 

 small and increasing. Thus it is in seeds germinating in 

 the dark: respiration increases day by day for a time, 

 though carbohydrate reserves are steadily decreasing. 

 Palladine 5 has investigated germinating wheat by analy- 

 zing the seedlings and determining the increase of the es- 

 sential (non-digestible) proteids day by day. The amount 

 of these proteids he regards as a measure of the amount 

 of actual protoplasm present. Assuming this to be so, 

 he finds an approximately constant ratio between the 

 amount of protoplasm at any stage and the respiration. 



As germination progresses in the dark the supplies of 

 reserve carbohydrate presently fail, and then the respira- 

 tion no longer increases in spite of the abundant proto- 

 plasm. According to our thesis the catalyst is now in 

 excess and the C0 2 production is limited by the shortage 

 of respirable material. 



This second type of case was more completely investi- 

 gated by Miss MatthaBi and myself in working on the 

 respiration of cut leaves of cherry-laurel kept starved 

 in the dark. For a time the C0 2 production of these non- 

 growing structures remains uniform, and then it begins to 

 fall off in a logarithmic curve, so that the course of res- 

 piration is just like C in Fig. 1. We interpret both phe- 

 nomena in the same way: in the initial level phase the res- 

 pirable material in the leaf is in excess, and the amount of 

 catalytic protoplasm limits the respiration to the normal 



of material is being exhausted, and we get a logarithmic 

 curve controlled by the law of mass, as much, it would 

 seem, as when cane-sugar is hydrolyzed in aqueous solu- 

 tion. 



After these two illustrations of the action of the law 



'Revue gen. de botanique, Tome VIII, 1896. 



