SUPPLEMENT 127 



and it is this chemical energy, as well as direct sunlight, that is employed in 

 carrying out the work of the plant. This is true both of the green and the non- 

 green plant ; for the latter is, as we have seen, dependent on the products 

 of assimilation manufactured by the green plant, so that light energy also 

 plays an important, though indirect, part in the nourishment of hetero- 

 trophic plants. Keeping in view, however, the immediate sources of energy, 

 we are bound to admit that these are partly light, partly that locked up in 

 nutrients. 



What we have now to inquire into is how the energy so provided is trans- 

 formed. The final expressions of energy appearing externally are those most 

 accessible to investigation, while we can form only a vague conception of the 

 changes taking place within the organism. Of these final manifestations of 

 energy, by far the most important is mechanical energy. The movements 

 carried out by the organism or by parts of it are manifestly amongst its most 

 remarkable, and hence also most thoroughly studied, activities. Thus the 

 production of heat is to be recognized as a phenomenon of very common occur- 

 rence, as to the significance of which we can, it is true, say but little, although 

 we are more accurately acquainted with its causes. In addition to the evolu- 

 tion of heat, mention must be made of the evolution of electric currents and 

 of light, two phenomena which as yet are of but minor importance in plant 

 physiology. 



398, 11. 33-6, for This third section . . . electricity, read It must now be 

 our task to study more in detail the origin of these forms of energy and to 

 elucidate their relationship to metabolism, and we may commence our inquiry 

 with a study of the evolution of heat. 



399, 1. 43, after (CoHN, 1893). add The considerable rise in temperature often 

 observed in piled-up hay is due to the agency of such thermophilous Bacteria. 

 According to MIEHE (1907) Bacillus coli and Oidium lactis raise the temperature 

 up to 40 C. and thus render it possible for B. calf actor, a genuine heat-producer, 

 to develop. The minimum temperature for this bacterium is about 30 C., and 

 it is capable of raising the temperature of the hay up to 70 C., which is its maxi- 

 mum. No such heating up takes place in sterilized hay. 



1. 48, after attained, read The heat produced is thus not a protection 

 against frost. 



1. 53, after plant read \ apparently this is not the case. 



400, 1. 3, for just read however 



1. 12, after night read (KRAUS, 1896). 



I. 21, for (1857) read ( l8 5*) 



II. 27-9, for an excess of ... Again, in cases read an excess of only 0-3 C. 

 as against 16-5 C. in normal respiration, and in Raphanus seedlings, 0-2 C. as 

 against 5-7 C. On the other hand, in cases 



I. 38, for increase . . . observed read increased production of heat accom- 

 panies increase in respiration (p. 202) 



II. 44-5, for or other . . . explanation read also by many other molecular 

 splitting processes, and in just this liberation of energy lies the importance 



I. 54, after heat read (often twice as much) 



401, 1. i, for and friction read mixing of fluids, imbibition, and finally 

 friction, 



II. 14-16, for This holds . . . many flowers read Indeed in BONNIER'S 

 experiments mature organs always gave off much less heat than could be 

 accounted for by the amount of respiration going on. The energy evolved in 



