THOMPSON YATES LABORATORIES REPORT 
long paths, although not purely spinal, is movement obtainable in the same side fore-limb and 
hind-limb by faradizing the side of the superior worm of cerebellum. In this case, differently 
from many spinal reflexes, both sets in antagonistic muscles are usually employed (one relaxing, 
other contracting — ' reciprocal innervation ').* I shall refer to this later in this paper. Its 
resemblance to the previous phenomenon may be but superficial. 
In my experience irradiation, ' spread^ is easier down the cord from fore-limb to hind-limb 
than across the cord from fore-limb to fore-limb. On the other hand, from hind-limb spread 
seems always easier across the cord to the opposite hind-limb, than up to the fore-limb even of the 
same side. 
Spinal Cross Reflexes 
By ' crossed reflex ' is understood a reflex involving travel of nervous impulses across the 
median plane of the cord. The need for the definition will be obvious in what follows. 
The 2nd of PFLtioER'st 'laws' of spinal reflexion — that termed the 'law of symmetry of 
bilateral reflexes ' — states that if to idio-lateral movement there be added, in the course of a spinal 
reflex, contra-lateral, the latter is symmetrical with the former. The Cat and Monkey afford 
several examples of this. 
Bilateral adduction of thighs (Macacus). 
Bilateral extension of hips, on stimulation of skin of abdomen (Cat). 
Bilateral abduction of hips, with some extension. 
Stimulus to fore-limb of Cat ; very similar extension and abduction of thighs by stimulating 
Ilnd cervical root. 
Bilateral protrusion of anus by stimulating one side of the perineum. 
Bilateral extension of elbows and retraction of shoulders by stimulating pinna (Cat). 
Bilateral flexion of elbows \\\x.\\ some supination of both forearms and a forward adduction of both 
fore-limbs, so that the paws cross each other in front of the chest, from stimulation of one fore-pad 
embrace reflex. 
Bilateral retraction of abdomen on stimulating the side of the chest or upper part of abdomen. 
Bilateral flexion of hips and knees on excitation of skin above an ischial tuberosity, in the Cat. 
Bilateral protraction of whiskers on excitation of skin of the face. 
But there are many and important instances which do not conform to the ' law.' A most 
important crossed reflex of progression elicitable from hind-limb of Cat and Dog does not conform 
to it. Under deep but not very profound anaesthesia, it is a common thing in these animals for 
alternating flexion of the two hind-limbs to take place. In the Rabbit the flexion of the two 
hind-limbs, which occurs under similar conditions, is synchronous, not alternate. After spinal 
transection at the top of the lumbar region, the same alternating flexion and extension often is 
started by merely lifting the animal so that the hind quarters hang. If, when the movement thus 
started has ceased and the limbs hang inactive, one hind-paw is pressed, the leg is drawn up ; and 
if the pressure be discontinued, or if the reflex activity is slight, the limb is let down again slowly. 
If the pressure be, however, continued or the reflex activity brisk, the drawing up of the limb is 
succeeded by movement of the opposite limb ; this crossed movement is usually extension of the 
knee, generally accompanied by extension of ankle (plantar-flexion), and slight extension at hip. 
* Sherrington, ' Proc. Roy. See.,' 1893. 
-f- ' Ueber d. sensorische Funct. d. Ruckenm,' Berlin, 1853. 
