208 
weismann’s theory of germ-plasm. 
Sep., 1890. 
proportionately smaller, how is it possible for the experiment 
to be repeated with success without allowing for adaptation 
through the influence of the environment ? It would seem 
infinity to one against it! 
The love for man displayed by domestic animals, and the 
feeling of security they evince when in company with him, 
are a further instance. Under domestication Natural Selection 
is suspended, and only those characters that have a commer¬ 
cial value stand any chance of being preserved; and as these 
(except perhaps in the dog and the cat) are not marketable 
qualities, it is hard to believe that the same mental condition 
should have arisen in such various creatures except through 
the influence of contact with man. 
Cases of inherited instinct in pointers. and sheep dogs, 
&c., might also be quoted, but most of them are insufficiently 
authenticated, and are worthless until more exact observa¬ 
tions have been made upon them. 
The case of the Bach family, mentioned by Spencer, in 
the “ Principles of Biology,” in which the faculty of music 
was distributed in a high degree over three hundred Bachs, 
is not admitted by Weismann as supporting the conclusion 
drawn from it. He argues that if the faculty arose and 
became intensified by continual practice, the most brilliant 
member of the family should be amongst the later ones, whereas 
the great Bach came in the middle of a line of lesser lights. 
Cases of hereditary diseases that make their appearance 
late in life, such as consumption, gout, epilepsy, &c., are at 
present used as powerful arguments against the theory ; but 
it is by no means certain that these diseases, which prove 
hereditary, are not the result of a variation in the germ of 
the person who first exhibits it. These were advanced 
against the theory in the discussion at Oxford, but at present 
the data are much too uncertain to justify a condemnation 
offhand. 
The one argument that Weismann admits to be a diffi¬ 
culty, is supplied by the well-known experiments of Brown- 
Sequard. I will not unnecessarily lengthen the paper by dis¬ 
cussing it, but simply state the facts. By means of a lesion 
of certain nerves, such as the severing of the sciatic nerve, 
by severing the spinal cord in the lumbar region, by remov¬ 
ing portions of the brain, or even by merely puncturing the 
spinal cord, of guinea-pigs, he produced all the symptoms of 
epilepsy. This is said to have been transmitted to the off¬ 
spring. Out of thirty cases, thirteen were perfectly healthy. 
In the experiments conducted by Obersteiner, out of thirty- 
two descendants of epileptic parents only two exhibited such 
