April 19, 1907] 



SCIENCE 



629 



covered by the term metabolism. Neverthe- 

 less, it points to the really important vital 

 process and it is broad enough to be in 

 harmony with all the facts we know. (If 

 respiration is taking in one gas and giving 

 out another, ' intramolecular respiration ' is an 

 absurdity in words.) There seems scanty 

 warrant for the custom of setting aside an- 

 aerobic respiration as though it were some- 

 thing entirely different or pathological or un- 

 usual. That aerobic and anaerobic respiration 

 and even fermentation are closely connected, 

 has for some time been recognized and has 

 been brought out with especial clearness by 

 Barnes." 



It may be urged that respiration in this 

 sense is too abstract and complex to be a 

 profitable subject for general teaching. With 

 this view the writer does not agree. Certainly 

 no amount of obscurity or complexity in an 

 essential process can warrant the adjustment 

 of definitions and teaching so as to lay the 

 emphasis on the superficial accompaniments of 

 that process. It seems to him that funda- 

 mental conceptions are the very ones to strive 

 for in general teaching. Teaching may not 

 go very far, but it ought to point in the right 

 direction. 



The suggestion made by Barnes' that a new 

 term ' energesis ' be adopted would be an ad- 

 mirable one, but the word respiration has so 

 long been prominent that it seems unlikely 

 that it will ever be permanently associated 

 with a minor meaning. Moreover, as already 

 stated, some of the best authorities already 

 use it in referring to the metabolic process of 

 energy release. For these reasons the writer 

 thinks it probable that this third definition is 

 the one which will stand. If this opinion is 

 well founded, it becomes the duty of teachers 

 to adopt the latter definition forthwith. What- 

 ever is done, the vital process is to be kept 

 in the foreground in teaching. 



The subject of respiration certainly de- 

 serves a more adequate treatment in our 

 courses. The writer knows as well as anyone 

 that topics are many and hours are few, but 



' ' The Theory of Respiration,' Science, Febru- 

 ary 17, 1905. * 



' Loc. cit. 



k 



are there not subjects in all our courses that 

 might better be omitted than a fair considera- 

 tion of a process which is essential and uni- 

 versal? Fundamental ideas penetrate the 

 student's mind but slowly, and the writer feels 

 that two or three experiments on the great 

 question of respiration are not too many. 

 After an experiment of some kind bringing 

 out clearly but only quantitatively the fact 

 that oxygen is absorbed and carbon dioxid 

 given off, let another be set up which shall 

 take some account of quantities — of different 

 phases of respiration. Peas and oily seeds 

 are valuable objects for this puipose. Ex- 

 planation of the real nature of respiration and 

 of the different kinds of respiration — an- 

 aerobic, fermentation, etc., will then follow 

 quite naturally. 



When students are using U tubes or thistle 

 tubes there is always a possibility that the 

 sealed end is not perfectly air tight. Eudiom- 

 eters over mercury are an admirable form of 

 apparatus, for here the question of leakage is 

 removed from discussion, and quantitative 

 readings can be made readily and with ac- 

 curacy. The seeds are held in the upper end 

 of the tube by glass wool, and in starting the 

 experiment the mercury column is introduced 

 some distance into the tube so that either in- 

 crease or decrease in volume can be noted. 

 The carbon dioxid evolved can later be directly 

 and accurately measured by introducing 

 caustic potash through the mercury. 



After a well-planned series of experiments 

 it is not difficult to question a class till 

 most of them perceive that the various phe- 

 nomena can be understood only in the light of 

 the fact that in each case energy is set free. 

 The content of the teacher's explanations 

 would then be something as follows: By 

 respiration we understand the changes brought 

 about by the cell whereby energy is released. 

 A supply of energy is a sine qua non, for life 

 and reactions which yield energy are uni- 

 versally carried on by living substance. Ordi- 

 narily respiration is a process of oxidation, 

 indicated both by an absorption of oxygen and 

 a production of carbon dioxid. A supply of 

 free oxygen seems to be necessary for proto- 

 plasmic movement and growth, and for con- 



