INSECT PARASITISM 435 



pending for his sustenance on his parents, brothers and sisters or re- 

 moter relations. At maturity, in addition to the possibility of becom- 

 ing parasitic on his wife, he has a choice of many kinds of social para- 

 sitism. As a member of a trust, political party or legislative body, not 

 to mention many other organizations and institutions, he may graft 

 successfully on the community at large or on some particularly lucrative 

 portion of it, and should he fail through these activities to store up a 

 sufficient corpus adiposum in the form of a bank-account, he may 

 parasitize, with advancing years and till the end of his days, on his own 

 offspring. 5 



But the roots of parasitism may be traced even deeper within the 

 very fabric of the organism itself. The theories of Roux and Weismann 

 have made us familiar with the struggle among the parts of the indi- 

 vidual organisms, i. e., among its organs, tissues, cells and the com- 

 ponents of its cells, a struggle in which these elements often grow and 

 develop at the expense of other elements in a manner that can only be 

 regarded as parasitic. The more modern theories of mutation and 

 Mendelism, with their insistence on unit-characters and " factors," 

 obviously admit of an interpretation in similar terms. We can even 

 shift this interpretation to the psychic plane, where we find the fixed 

 ideas, obsessions and monomanias behaving as so many processes which 

 draw their sustenance from other psychic processes to such an extent 

 that they may in the end not only dominate but destroy the whole per- 

 sonality. 



Some of you will be shocked at this account of what we are in the 

 habit of describing in very different language, for the same emotional 

 reason that we all admire the tiger and the tiger-beetle and loathe the 

 tape-worm and the louse, namely, because our instinctive horror of the 

 parasites to which our species is so constantly exposed, prevents us even 

 as twentieth-century zoologists from appreciating the extent to which 

 all life, ourselves included, is saturated with parasitic proclivities. I 

 fear, however, that this attempt to justify my shocking language will 

 fail to convince some others among you, who will accuse me of being 

 myself a host of one of the obsessions to which I have just alluded — of 

 the parasitic obsession, namely, of the idea of parasitism. You will 

 say that in thus subtilizing or volatilizing what has always seemed to 

 be a concrete biological phenomenon, and in thus diffusing the concept 



3 Certain general aspects of social parasitism in man are admirably presented 

 by Massart and Vandervelde in their work entitled "Parasitisme Organique et 

 Parasitisme Social," Bull. Sci. de France et de la Belg., XXV., 1893, 68 pp., and 

 by Eoss in Chapter XXVIII. of his "Social Control," Macmillan Co., New 

 York, 1910. The conception of viviparity as a form of parasitism has been 

 developed by Giard ("Sur la signification generale du parasitisme placentaire, " 

 C. E. Soc. Biolog., 1897), Houssay ("La Forme et la Vie. Essai de la Methode 

 Mecanique en Zoologie," Paris, 1900) and Faussek ("Viviparity and Para- 

 sitism," in Eussian, Busskoje Bogatswo, 1893). 



