DOUGLAS M. SURGENOR 



in catalytically small amounts. Thus the relative numerical 

 inferiority of properdin belies the probable significance of this 

 substance to the basic defense mechanisms of the body, a- 

 Lipoprotein molecules occur four times as frequently as j3- 

 lipoproteins, although there is twice as much of the latter by 

 weight. Moreover, despite relatively high molar concentra- 

 tions, precise functional roles have not yet been ascribed to the 

 ^-lipoproteins, acid glycoprotein, or Q!2-glycoproteins. Although 

 the plasma components represented in Table I account for ap- 

 proximately 85% of the protein weight, they comprise consider- 

 ably less than half of the protein species known to be present in 

 plasma. The latter have not been included in Table I because 

 they have not yet been characterized in the necessary parameters. 

 It is safe to estimate that the majority of components not listed 

 would fall at the low end of the numerical spectrum. 



The dissection of blood into its molecular and cellular parts 

 has contributed greatly to the study of the biochemical mech- 

 anisms by which the manifold functions of the blood are accom- 

 plished within the body. In attempting to assimilate such knowl- 

 edge into a rational picture, one parameter may be overlooked. 

 Unlike the anatomist, who can extrapolate back from his dis- 

 sected parts to the gross morphology of the organisms, we must 

 ask ourselves whether the blood we started with, e.g., our unit 

 volume, was a suspension of formed elements in a random solu- 

 tion of plasma proteins, or inight there perhaps have been a 

 chemical morphology which was unintentionally disrupted when 

 the blood was removed from the circulation or, more likely still, 

 when the unnatural chemical and physical instruments of dis- 

 section were applied? Obviously no categorical answer can 

 be made to this question. On the other hand, there is good evi- 

 dence for the existence of favored orientations within the blood ; 

 the possible role of the platelet in attracting a selected environ- 

 ment of clotting factors has already been noted. The natural 

 occurrence of rouleaux within the circulatory network brings 

 to mind the selective interactions of red cells and certain asym- 

 metric plasma proteins, including fibrinogen and the ai-m\ico- 



672 



