RESPIRATION OF SEED8. 81 



coiiclusioiis which they have drawn. It is now dotinitoly known that 

 all cheniical actions do not cease at the temperature of li((uid air. Thus 

 it can not ))e ^-ranted tliat the protoi)hisni l)eeonies inert as a result of 

 the reduction in temperature. Maciuenne" more nearl}^ expressed the 

 true coii.ditions applicable to low temperatures when he wrote that 

 with dessication, at low temperatures, seeds are transformed from a 

 condition of diminished activity into a state of suspended life. But 

 there are still other factors to be considered. The vegetative functions 

 may cease, metabolic processes may be at a standstill, intramolecular 

 respiration need not exist, yet vitality is not, nor ever has ))een, pre- 

 served; sooner or later life l>ecomes extinct. What does this signify? 

 The gradua'l process of devitalization means chemical change, and 

 chemical change means activity within the cells. We uuist not forget 

 the great complexity of the composition of the protoplasmic ])odies 

 wdiich go to make up a seed. The chemistry of the living cell is still 

 surrounded l)y manj^ difficulties and is likewise Ulled with many sur- 

 prises, and ])efore the question of the vitalit}' of seeds can be under- 

 stood a more comprehensive knowledge of both the functions and 

 composition of the cell contents is necessary. 



It is well known that all organic compounds are made up of a very 

 few elementary substances, ])ut the numerous and obscure ways in 

 which the}^ are put together furnish questions of the greatest per- 

 plexity. Substances having the same elements may diHer widely as 

 to their properties. Moreover, isomeric substances — i. e., those hav- 

 ing the same elements in the same proportions, giving an equivalent 

 molecular weight — are usually very different in their chemical reac- 

 tions and ph^^siological functions. As j^et this intramolecular atomic 

 rearrangement is but vaguely understood, and the writer ventures to 

 suggest that with a more comprehensive knowledge of the chemistry 

 of the living cell some such chemical activity will be discovered. 

 With these discoveries will come, perhaps, an understanding of the 

 devitalization of seeds, and with it the theory of the immortality of 

 seeds will vanish. 



SUMMART. 



(1) Seeds, like other living organisms, respire when subjected to 

 normal conditions of storage. 



(2) Respiration means a transformation of energy, and consequently 

 a premature death of the seed. 



(3) Within certain limits respiration is directly proportional to the 

 amount of water present in the seeds and to the temperature at which 

 they^ are stored. 



(4) B}^ decreasing the water content of seeds respiration is reduced 

 and vitality greatly prolonged. 



«Cornpt. Rend., 134: 1243-1246, 1902. 

 25037— No. 58—04 6 



