i 
750 THE RELATION BETWEEN ORGANIC VIGOR AND SEX. 
males as well as females. Packard’s expression is that ‘ the asex- 
ual Aphis and the perfect female may be called dimorphic forms.” 
Of the three forms, then, that one whose production especially 
attends the conditions of the lowest vitality is the male. 
But another class of facts of a quite different kind may be 
considered in this connection ; involving higher animals and even 
man himself. I refer to the history of monstrosities. Double 
monsters (of which some remarkable human instances have been 
exhibited within a few years in this country) are always of one 
sex and nearly always of the female sex.* There is reason to 
exclude from this class of true double monsters cases like that of 
the Siamese Chang and Eng, who may be regarded as really twins 
with two complete bodies abnormally united together. 
Now, why should a double fœtus nearly always, have the female 
sex? The bearing of this question upon that which we have just 
been discussing appears, when we consider the true theory of double 
monsters. Under the close investigations of St. Hilaire, Virchow, 
Vrolik, Fisher and others} it has been made quite evident that 
they result not at all from the fusion of two embryos into one, 
but, on the contrary, from the abnormal fission of a single ovum, 
under excess of formative force. The point for us now to notice 
is the nearly constant association of this profusion of develop- 
mental force with femininity of sex. 
Regarding the actual function of this force (however we may 
designate it, as, €. g., life force, organic force, bio-plastic force, 
ete.) as being the formation of plasma with attendant cell-multi- 
plication or vegetative repetition, it would appear that this is pre- 
cisely what, in plants and animals, may be the especial feminine 
endowment. The two directions or modes of manifestation of 
this organic force are individual construction and reproduction. 
These may, therefore, be in inverse proportion to each other, 
simply because the energy or material consumed in the one process 
is taken from the other; and yet, while a certain limitation of 
food and temperature favors reproduction, rather than individual 
nutrition and construction, a greater lowering of these conditions 
of vitality will retard, arrest or degrade both processes. Accord- 
ing to Meehan’s interpretation of his a aaron 
*G. J. Fisher, Trans. Med. Soc. of New York, 1865-1868. neg this I find only à ne 5 
vague expression of W. Vrolik (Cyclop. of Anat. and Physiol, Art. Teratology, P- 
946) that “ some sorts ” of double monsters are more frequ sacia male. 
t Goodell, Phi . Med. Times, June 15, 1871. 
