82 THE VITALITY AND (}P:RM1NATI()N <)F SKEDS. 



(5) 111 most seeds the (iiuiutity of oxygen absorbed o-rcatly exceeds 

 the (|uiintity of carbon dioxid evolved. 



(()) Respiration is nearly as active in the dark as in the light. 



(7) Respiration apparently is not necessary for the maintenance of • 

 seed life. 



(8) A cessation of respiration does not mean a cessation of chemical 



activities. 



ENZYMES IN SEEDS AND THE PART THEY PLAY IN THE 

 PRESERVATION OF VITALITY. 



During the past decade the so-called unorganized ferments have 

 taken an important place among the subjects of biological research. 

 Our knowledge of their wide distribution has increased many fold. 

 The part they play in both anal)olism and catabolism has furnished us 

 many surprises, but with all of the work that has been done our knowl- 

 edge of these most complex compounds is very limited. 



The part that enz3niies pla}^ in the processes of germination is of the 

 utmost importance. It is now quite well understood that they are 

 developed as germination progresses. They act on the most complex 

 reserve food products, converting them into simpler substances that 

 can be more readil}^ utilized by the growing seedling. 



However, even in this connection there is a great diversity of opinion, 

 especially as to their distribution and enzymic action within the endo- 

 sperm itself. Puriewitsch,'* Griiss,^^ and Ilansteen '-' are cited b}^ Brown 

 and Escombe'^ as holding the view that the amyliferous cells of the 

 endosperm of the grasses can digest their reserve materials independ- 

 ently of any action of the embryo — i. e., the starch -bearing cells are 

 living cells and secrete enzymes in the grasses as well as in the coty- 

 ledonous cells of Lv/plmis^ Phaseolus, and liicmm. In 1S90, Brown 

 and Morris^ did not find such to be the case; but the results of Purie- 

 witsch, Griiss, and Hansteen led to a duplication of the experiments 

 by Brown and Escombe in 1898. At this time they demonstrated that 

 the am3diferous cells pla}" no part in the chemical changes which take 

 place during the process of germination, but on the contrary that the 

 enzymic action in the endosperm of the grasses is confined to the 

 aleuron layer. 



But the purpose of the present paper is not to consider the localiza- 

 tion of the particular enzjane, and nmch less the action of enzymes 

 during germination. At this time quite another question is to be 



«Pring,sheims Jahrb., 31: 1, 1897. 



b Landw. Jahrbiicher, 1896, p. 385. 



<^ Flora, 79: 419, 1894. 



rfProc. Roy. Soc, 63: 3-25, 1898. 



«Jour. Chem. Soc, London, 57: 458-528, 1890. 



