246 



SCIENCE 



[N. S. Vol. XXIX. No. 737 



tions is a strong point on tlie side of the 

 importance of phagocytosis in their heal- 

 ing, whatever other measures, of which at 

 present we know less or nothing, may be 

 in operation also. 



Whether the opsonic action of serum is 

 caused by distinct and independent sub- 

 stances or by antibodies with other actions 

 as well, has been an interesting question 

 concerning which there is still difference 

 of opinion. The question now seems to be 

 narrowed down to whether the opsonins 

 and lysins are the same, some claiming 

 that opsonification merely is the result of 

 an early stage of lysis before actual solu- 

 tion takes place. Opsonins would appear 

 to be distinct from other antibodies be- 

 cause a given serum may be opsonic, but 

 not lytic, while the reverse probably also 

 occurs. But here certain difficulties arise. 

 While it is weU established that serum may 

 be strongly opsonic without being lytic 

 and without even containing lytic ambo- 

 ceptor so far as our present methods indi- 

 cate, the suggestion is made that in such 

 cases the failure to obtain lysis may be 

 owing to the state of the object tested and 

 not to the absence of lysins. This con- 

 sideration applies with most effect to in- 

 stances in which we know the bacterium 

 or corpuscle is susceptible both to lysis 

 and to opsonification, and in which lysis 

 might not take place either because the 

 serum was not active enough or because 

 of some special resistance to lysis. The 

 explanation falls short, however, when 

 applied to bacteria like pneumococei and 

 streptococci, which, while readily opsoni- 

 fied, are yet insusceptible to lysis. In this 

 case the claim that lysis does not take 

 place because of the physical state of the 

 bacteria is merely an assumption. 



If opsonification and lysis depend upon 

 the same body the opsonic and lytic powers 

 of the serum of an animal in the course of 

 immunization should always run parallel. 



If they do so that fact does not of itself 

 prove that it concerns one body, but fail- 

 ure to run parallel would indicate the ex- 

 istence of separate bodies with different 

 functions. Actual observations show that 

 in certain animals single injections of 

 alien red corpuscles may increase the op- 

 sonic power of the serum for that cor- 

 puscle a hundred times or more above 

 normal, while the Ij^ic power for the same 

 corpuscle may be increased comparatively 

 much less and in some conditions not at 

 all. On this account, then, as well as for 

 other reasons, the view that opsonins, 

 meaning thereby the thermostable opsonic 

 substances, constitute a distinct class of 

 antibodies, seems to me to be correct. 



That the activating or complementing 

 opsonic substance is closely related to the 

 complement of lysis is indicated by a num- 

 ber of considerations: Both are sensitive 

 to the action of heat, being destroyed by 

 an exposure of thirty minutes to 58-60° 

 C. ; both appear to be split up into two 

 distinct components by water, and both 

 are neutralized by a number of ionizable 

 salts. As stated before, the opsonic com- 

 plement, however, seems to remain free in 

 the phagocytic mixtures, whereas the com- 

 plement of lysis is regarded generally as 

 bound by the amboceptor. 



We come now to a most interesting part 

 of our subject, namely, the resistance of- 

 fered by microbes under different condi- 

 tions to antibodies and more particularly 

 to opsonins. 



Since the discovery of the chronic 

 microbe carrier the adaptation of microbes 

 to the defensive mechanisms of the animal 

 body is no longer merely of academic in- 

 terest. Under the conception that phago- 

 cytosis and bacteriolysis form the basis of 

 healing and immunity in perhaps most of 

 the infectious diseases, the infecting mi- 

 crobes should disappear at the time of 

 recovery. This is probably the general rule, 



