1888.] Prof. Haycraft on Reflex Scratching Movements. 139 
claws. The dog cannot do this, and the hind leg is used instead. 
The rabbit has a mobile and flexible body, which it cleans in a 
sitting posture with its mouth and fore paws. The guinea-pig and 
the ox are shorter, with thick -set necks, and the hind leg is called 
into requisition. 
One cannot attain spinal scratching reflexes from the human sub- 
ject, and probably not from the apes. The theory of build, and 
bodily mobility, will not entirely explain these cases, however, 
for another consideration appears. This we shall now consider. 
Co-ordinated reflex movements may be divided into two classes. 
In the first class we have movements of limbs, the aim of which is 
to bring them into relationship with other parts of the body. Such 
are the complex movements of the pithed frog, and the scratching 
movements we are discussing. In these cases all that is essential 
for the acquisition of the power of bringing one part of the body 
into connection with another part is tactile sensibility of the skin. 
The other classes of co-ordinated reflexes are those which change the 
position of the body in respect to its surroundings, e.p., walking, 
swimming, &c. In this case sensation of sight, hearing, &c. are 
required in addition. 
The nerves of tactile sensibility for the trunk and limbs pass to 
the cord in which they make connection with motor-fibres passing 
to those parts of the body. The nerves of hearing, sight, &c., pass 
to the brain. 
It follows from this that the first class of movements may take 
place in a pithed animal; the latter, never. Now, one constantly 
finds the remarks that spinal, co-ordinated movements present in 
lower animals, e.g., the frog, have their centres in higher regions of 
the nervous system in higher animals. This and similar remarks 
indicate, I think, a grave misconception. 
The second class of co-ordinated movements are never purely spinal 
either in the frog or in any other vertebrate. It is probable in 
those cases of the first class, in which the co-operation of the brain 
with the spinal cord is necessar^q that this is not the result merely 
of higher development, but depends upon other causes, some of 
which I have touched upon. 
The scratching movements, quite as complex as any of the move- 
ments of the pithed frog, require for their performance the cord 
