INTRODUCTORY DISCUSSION. 21 



respiration. Undoubtedly the economic coefficient varies greatly in dif- 

 ferent plants, and in all probability heat is to a large measure only the 

 unavoidable accompaniment of catabolism, and the plant must use other 

 forms of energy for the synthesis of formative material. The results of the 

 very extensive and thorough work which has been done in the field of 

 mammalian physiology on this subject as yet find very little application to 

 the problems in the plant. This, of course, is not surprising in view of the 

 fundamental differences in the normal mode of life and functions between 

 plants and animals. 



There is as yet no definite way of determining the form in which energy 

 is released and utilized in the processes in the living plant Practically the 

 only factors which so far have been within the range of experimental investi- 

 gation have been the study of the end-results and outer manifestations of 

 the energy transformations. For the majority of plants the liberation of 

 heat is probably the most general. The very interesting experiments of 

 Bonnier 1 indicate that this varies greatly under various conditions and 

 stages of development By comparing the heat liberated with the theoretical 

 amount possible by simple combustion calculated from the absorption of 

 oxygen and liberation of carbon dioxid, Bonnier found that the former 

 often greatly exceeds the latter, while in other cases, as in mature plants, 

 the heat liberated was decidedly lower than the amount calculated from 

 their respiration. While these results but indicate the transformations of 

 the obscure chemical energy, it would be highly desirable to elaborate 

 investigations of this nature, and to do so in collaboration with a study of 

 the energy relations of the intricate chemical dissociations discussed above. 

 Investigations thus far undertaken have not contributed greatly to a fuller 

 understanding of the subject, as in the measurement of heat liberated 

 little attention has been paid to the chemical changes and the nature of 

 exothermic reactions involved. 



Of interest in this connection are the old observations of Radzisezewski * 

 who studied the phosphorescence which is produced in plants and animals 

 and which also accompanies the autoxidation of a very large number of 

 organic compounds. He interpreted his findings on the basis of the old 

 Schonbein theory of oxidation, and showed that all substances which by 

 oxidation Schonbein had noticed formed hydrogen peroxide and active 

 oxygen also produced light, and generally at ordinary temperatures. 

 Eadzisezewski was the first to observe that sodium hydroxide induces this 

 phosphorescence in many organic compounds ; e. g,, all aldehydes and their 

 ammonia derivatives, the higher alcohols (it has since also been observed 

 with sugars), fats, the higher fatty acids, the soaps, and a large variety of 

 others. Knowledge of the liberation of other forms of energy besides heat 

 in the dissociation and oxidative reactions induced by catalysts may be of 



*BONNIEB, G. Recherches sur la chaleur v6g6tale, Ann. Science Nat. Serie, VII, 



18, 1, 1893. 

 'RADZISEZEWSKI, M. Ueber der Phosphoriscenz der organischen und der organi- 



sierten Koerper, Lieblg's Ann. der Chem., 203, 305-336, 1881. 



