LECT VII. CATALYTIC ACTION. 139 



which consists in the colouration of the osseous parts of 

 animals fed with colouring substances, and then in their 

 decolorization when such nutrition is stopped, has always 

 appeared to me insufficient. It must, however, be admitted 

 that physiological facts, generally support the idea of this 

 renovation. 



If I were here to mention to you the various kinds of 

 experimental information still wanting, and which are 

 necessary to elucidate the function of nutrition, I should 

 occupy much more of your time than if I undertook to de- 

 scribe all that we really know on this subject. 



Catalytic Action of the Blood Globules. The blood glo- 

 bules, making no part of the tissue, though being essential 

 to nutrition, may, with a certain amount of probability, be 

 regarded as the catalytic body which promotes the trans- 

 formation and continual renovation of the tissues. An 

 analogy of this characteristic of the globules is to be found 

 in the necessity which they experience of being charged 

 with oxygen in order to acquire this property. 



Observe also that as in vegetables, diastase converts 

 starch into dextrine, which is afterwards formed into cellu- 

 lose and wood, that is to say, into bodies which are iso- 

 meric with each other, so [in animals] the blood globules 

 change albumen into fibrine, a transformation which cer- 

 tainly occurs in the embryo. 



I wish I were able to say that the reality of these changes 

 had been demonstrated as in the case of starch. I have 

 made a great many experiments, having this object in 

 view ; but the results which I have hitherto obtained still 

 leave me in doubt. I kept for a month at the constant 

 temperature of + 40 centig. [= 104 Fahr.,] the albu- 

 men of the egg mixed with a small quantity of the blood 

 globules of a fowl in the presence of oxygen. A receiver 

 used for collecting water offered me the convenience of a 



