SECT. 6] OF THE EMBRYO 937 



Hayes, on the other hand, found exactly the opposite on the Atlantic 

 salmon; a rising instead of a falling P.E.G.; 0-36 before the looth day 

 and 0-52 afterwards. Obviously a further extension of our knowledge 

 of plastic efficiency coefficients would be very desirable. 



The effect of temperature upon the P. E.G. raises an interesting 

 problem. For the mould, Aspergillus niger, Terroine & Wurmser in 

 their classical paper, could find no difference, thus 



Temperature ° C. P.E.C. 

 22 0-44 



29 0-43 



36 0-43 



38 0-44 



They therefore concluded that although in a given time the amount 

 of mycelium formed would be less at the lower temperature, the 

 amount of material combusted would be correspondingly less. Com- 

 bustion would always go parallel with storage. Rubner found much 

 the same thing in the case of the growth of Proteus vulgaris, and 

 Terroine & Wurmser were led to formulate the general rule "that 

 the quota of material and energy utilised during a given piece of 

 biological work, does not vary appreciably within the limits of 

 temperature compatible with life, although the rate at which the 

 work is done will, of course, vary greatly with temperature". In 

 general this conclusion was supported by the experiments of Terroine, 

 Bonnet & Joessel with germinating seeds (for further discussion of 

 this work see Appendix iv) 



Next Barthelemy & Bonnet examined the development of frog 

 embryos at various temperatures, and obtained for the P.E.C. the 

 following results : 



^ Temperature ° C. P.E.C. 



1st series ... 8 0-88 



10 0-51 



14 0-54 



21 0-49 



2nd series ... 8 0-85 



10 0-79 



14 0-84 



21 0-83 



