18g0.] f Embryology. 587 
that various lesions of nervous substance in guinea-pigs are followed 
by epilepsy, and the offspring are often affected with nervous disorders, 
and sometimes with epilepsy. He defends his theory in two ways, 
first, by referring to infection as the true cause, and not heredity (p. 
82, pp. 312-315); secondly, by pointing out the difficulty of con- 
ceiving the method of transmission upon either a preformation or 
epigenetic theory (pp. 315-319). Both these lines of argument are, it . 
will be noticed, in the region of hypothesis and supposition, 
As to the first point, there is no distinct evidence, as he himself 
admits, that epilepsy is caused by bacillus; and, in fact, in some cases 
it cannot be (p. 314), and yet he conceives that the transmission is by 
a bacillus from an infected part reaching to and attacking germ-plasm. 
The question here, as often elsewhere in the Essays, is resolved not so 
much into a matter of fact as a matter for conception. But how does 
the bacillus hypothesis simplify the problem for the imagination? If 
the microbe reaches the germ-cell how can it attack it any more than a 
“ molecule of the brain of an epileptic animal ?’’ (p. 310). If it could 
attack the germ-plasm, we have still the same fundamental difficulty as 
with transmission of acquired character, namely, as to how the bacillus 
can excite in the germ, not epilepsy itself, which is impossible, but 
such a peculiar disturbance of some peculiar molecular order that 
epilepsy will result after the many stages of evolution in a certain part 
of acertain tissue in the developed animal. That is, we must bring 
against the bacillus theory the same objection which he brings against 
the epigenetic when he asks how the germ-plasm can receive, ‘‘ not 
indeed the peculiar structure of the stage itself, but such a molecular 
constitution as will ensure the ultimate appearance of epilepsy in the 
offspring.” (P. 318). Prof. Weismann concludes that there is trans- 
mission, but one ‘‘ which cannot depend upon heredity, and is in all 
probability due to infection.’’ But if this method of infection is ad- 
mitted, do we not have here, in a wide but true sense, heredity, a real 
transmission of acquired character, the acquired infectious (?) disease 
is transmitted to offspring ; the offspring alike inherit it, whether we 
suppose the method of transmission to the sperm or germ-cell be by 
transference of bacillus, or of diseased molecules, or of gemmules, or 
any other way. By acknowledging that the continuous germ-plasm is 
affected, no matter how, but by or through acquired charactcr, so that 
the character reappears in offspring, does not Prof. Weismann really 
concede the point at issue z 
With reference to the second point, the reductio ad absurdum of 
other theories, it is quite possible to urge against the continuity theory 
