446 



Dr. W. M. Fletcher and Prof. F. G. Hopkins. 



" giant " molecule, as he described it, made unstable by the inclusion within 

 it of what he called " intramolecular oxygen," was the same in all essentials 

 as the inogen molecule of Hermann. 



These conceptions of Hermann and Pfliiger have bad an historical 

 importance reaching far beyond the particular enquiry into muscular 

 energy. They summarised the only aspects of cell metabolism which had 

 received any experimental analysis at all, and up to the end of the 

 nineteenth century they not only represented all that was known of cell 

 respiration and of its relations to cell energy, but they dominated also all 

 our ideas of cell metabolism in general. It was conceived that the 

 chemical processes of life in all cells consisted essentially in the building up 

 of elaborate, unstable, and oxygen -charged molecules, by the processes of 

 so-called " anabolism/' into the mystical complexes of irritable protoplasm. 

 From protoplasm, as seen in chemical imagination, a descent by the stages of 

 so-called " catabolism " was conceived to follow, by which through successive 

 splitting processes energy was discharged, and certain recognisable end- 

 products were displayed. 



Michael Foster, a name familiar and loved in this place no less than in 

 Cambridge, wrote in 1895 as follows : — 



"The oxygen taken in by the muscle, whatever be its exact condition 

 immediately upon its entrance to the muscular substance, in the phase 

 which has been called ' intramolecular,' sooner or later enters into a 

 combination, or, perhaps we should rather say, enters into a series of 

 combinations. "We have previously urged that all living substance may be 

 regarded as incessantly undergoing changes of a double kind, changes of 

 building up, and changes of breaking down. . . . We cannot as yet trace 

 out the steps taken by the oxygen from the moment it slips from the blood 

 into the muscular substance to the moment when it issues united with 

 carbon as carbonic acid. The whole mystery of life lies hidden in the 

 story of that progress, and for the present we must be content with simply 

 knowing the beginning and the end."* 



The story of that progress is part of the story we have to tell to-day, and 

 these words of Foster may be taken as the summary of what was the 

 current physiological opinion some eighteen years ago, when the work now 

 to be discussed began at Cambridge. 



"We must note first that the inogen theory had two main bases of 

 experimental support. These were : — 



(1) The contraction of muscle and the death of muscle alike were believed 

 * ' Text Book of Physiology ' (Sixth Edition), Book II, p. 610. 



