652 SUMMARY OF CURRENT RESEARCHES RELATING TO 



by plants, chiefly by germinating, starchy, and oily seeds, ripening 

 fruits of Ricinus communis and Papaver somniferum, and flower- 

 buds of the last species. The following are some of the more 

 important results : — 



1. In the germination of both oily and starchy seeds, during 

 the period of swelling, the volume of the exhaled carbonic gas is very 

 nearly the same as that of the inhaled oxygen. 



2. When access of oxygen is hindered, as when the swelling takes 

 place under water, intramolecular respiration comes into play ; and 

 this may even continue after the seeds are exposed to the direct 

 influence of the air. 



3. When, in oily seeds, the roots begin to grow, the quantity 

 of inhaled oxygen begins to show an excess over that of the exhaled 

 carbonic acid. At the time when growth and respiration are most 

 active, about 55-65 parts of carbonic acid are exhaled for 100 parts 

 of oxygen inhaled. 



4. The transformation of oil into starch is probably effected by 

 each molecule of oil splitting up into three molecules of starch, 

 together with carbonic acid, water, and other undetermined 

 substances. 



5. In the later periods of the germination of oleaginous seeds, 

 not only the oil but also the carbohydrates formed from it, are 

 used up in respiration ; in consequence of which the volumes of 

 oxygen inhaled and of carbonic acid exhaled become eventually 

 equal. 



6. In the germination of starchy seeds the volumes of the two 

 gases remain constantly nearly the same, varying somewhat with 

 different species. 



7. In the case of expanding buds (of Papaver somniferum) the 

 volumes of the two gases are the same. 



8. In the case of ripening fruits containing oily seeds, a con- 

 siderably greater quantity of carbonic acid is exhaled than that of 

 the oxygen inhaled, a process of reduction taking place by which 

 starch is changed into oil. 



9. Changes in the pressure of the oxygen cause corresponding 

 changes in the energy of respiration. 



10. But even when the energy of respiration is affected in this 

 way, no alteration takes place in the relative quantity of oxygen 

 inhaled and of carbonic acid exhaled. The relative proportion is 

 affected only when the pressure of oxygen is so reduced that the 

 amount of this gas inhaled is considerably diminished, giving rise 

 to intramolecular respiration. 



11. Intramolecular is no ingredient in normal respiration, which 

 is the result of the direct action of atmospheric oxygen on living 

 molecules of protoplasm ; the former taking place only when normal 

 respiration is hindered by a deficient supply of oxygen. 



12. Under the ordinary conditions of normal respiration, intra- 

 molecular respiration takes place only when a process of reduction 

 is going on at the same time in the plant, as when carbohydrates 

 are being transformed into oil. 



