THE RECEPTOR APPARATUS OF THE RED BLOOD-CELLS. 399 



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are regenerated must, of course, excite the greatest interest. It 

 can be conceived that ceitain portions of the functional central 

 group [Leistungskern] can fix combustible molecular groups, and that 

 these groups are thus rendered more susceptible to complete com- 

 bustion." 



It is at once clear that these fixing portions, which I now term 

 receptors, correspond exactly m their nature to the biogen residues 

 of Verworn. 



Probably no one who has seriously studied these questions will 

 question the importance of these deductions. In spite, however, 

 of the decades which have elapsed since Pfluger's publication we have 

 not advanced one step in our experimental knowledge of this sub- 

 ject, a fact which is due to the endless difficulties occasioned by the 

 nature and instability of the living material. I hope that my theory 

 is destined finally to bridge this wide gap. The knowledge that the 

 numerous antibodies are nothing more than thrust-off receptors of 

 the cell should make it possible to get at the nature of assimilating 

 processes. By means of immunization we can compel the thrusting- 

 off of certain particular receptors which then collect in the serum. 

 Free from the disturbing connection with the protoplasm, they no 

 longer offer any difficulties for biochemical investigations. Viewed 

 in this light, I believe that the facts which I have determined con- 

 cerning the action of uniceptors and amboceptors constitute a new 

 step toward a true conception of the vital processes. 



It can hardly be doubted that the red blood-cells, owing to their 

 relatively simple structure and the ease with which they can be 

 manipulated, are better adapted for these purposes than other cellular 

 elements. I also believe that clinical investigations are destined to 

 play a leading role in the solution of these problems, simply because 

 the various types of disease offer a much greater variation in the vital 

 conditions than we can attain by means of experiments. Even 

 aside from the gain to pure biological science, clinical medicine should 

 derive the greatest advantage from such studies, for, as already men- 

 tioned, they deal with the true conception of the pathology of the 

 red blood-cells. 



In order somewhat to facilitate such a study it may perhaps be 

 well to give a brief sketch of the facts which in conjunction with 

 my colleague, Dr. Morgenroth, I have discovered regarding the 

 physiology of the receptors. 



Considering the large number of receptors which each species 



