Different Animals, Ge. 507 
6. Dr. Clarke informs us in the same paper, 
** that in orher cases, where the brain has been 
perfect, the spinal marrow has been deficient in 
a great part of its extent and sometimes through- 
out” p. 159: But I do not recollect an instance 
of this kind and Soemmerring says:—‘ Non 
raro spine medulla est sine cerebro, numquam 
vero cerebrum sine spine medulla est visum, 
deficiente enim spine medulla, cerebrum simul 
abfuit.’’* 
§ II. 
On the influence of original defects in the nervous 
system of man on sensation and voluntary motion. 
From considering merely the laws of sensation 
and voluntary motion, mentioned above, as 
obtaining in a perfectly formed human being, a 
person might be led to conclude a priori, that a 
fetus, having no brain, or neither brain nor 
spinal marrow, must necessarily be destitute of 
sensibility and incapable of throwing into action 
any of the muscles subservient to voluntary 
motion. 
However, when he considers, that the human 
* De Corporis Humani Fabrica T. IV. p. 89: where © 
he refers to Huser de Medulla Spinali, Go6tting. 1789. 
P+ 45 
‘ 
