OXYGEN RESPIRATION 7 



throughout to that of the grand period of growth/ During 

 the first days of germination the respiratory energy gradually 

 increases, finally reaches a maximum and then decreases again 

 at the end of germination. This connection between the curves 

 is easily understood. The mechanical energy required for the 

 formative processes of growth is developed in the respiratory 

 processes. An increase of energy consumption requires a cor- 

 responding increase of energy production. Careful experi- 

 ments showed that embryonic, growing organs respire more 

 vigorously than endosperm.^ 



In the ripening of seeds the energy of their respiration grad- 

 ually becomes weaker and reaches a minimum value at the 

 time of the complete dessication of the mature seeds.- 



There is an intensive respiration in flowers which in general 

 develop quickly and last but a short time.^ According to the 

 data of de Saussure,^ sexual organs respire more vigorously 

 than involucral leaves. After pollination the respiration of the 

 fruiting growth becomes very vigorous, a condition which is 

 obviously connected with the formative processes in the organi- 

 zation of the embryo. 



The analyses of de Saussure show that the respiratory energy 

 of flowers reaches a value of 2-^}-i times that of foliage 

 leaves.^ According to the most recent data, leaves which are 

 rich in anthocyanins exhibit especially \dgorous respiration. 

 With these the oxygen absorption is said to be very great.® 

 The chlorophyll free, parasitic phanerogams respire fairly 

 intensively according to the older researches of various writers. 



1 Burlakoff. Arb. d. Naturf.-Ges. Charkow. Suppl. i to vol. 31. 1897. 



2 Appleman and Arthur. Amer. Jour. Bot. 5: 207. 1918; Jour. Agr. Res. Vol. 17, no. 4. 



1919. 



3 de Saussure. Rech. chim. sur la vegetation. 1804; Ann. de chim. et de physique. 

 (II) 21 : 279. 1822. 



« de Saussure. /oc. ci^.,- Cahours. Compt. rend. 51 : 496. 1864; Maige, A. Ibid. 142: 

 104. 1906; Rev. gen. de bot. 19: 9. 1907; Maige, G. Ibid. 21: 32. 1909. 



s de Saussure. loc. cil. 



« Nicolas, G. Compt. rend. 165 : 130. 1918. 



' This is the well-known sigmoid curve of autocatalysis. It is only recently, 

 however, that the conception of growth as an autocatalytic process has been 

 correctly applied in deriving the exact equation for a given growth curve. Cro- 

 zier (J. Gen. Physiol. 10: 53-73. 1926-27) has shown how precisely the growth 

 of an animal (the rat) and a plant (sunflower) follows the correct equation for 

 autocatalysis. The grand curves of both plant respiration and plant growth 

 should be further tested bv the same method. — Ed. 



