134 THOMPSON YATES LABORATORIES REPORT 
a rest is allowed. To increase the intensity of the stimulation is not of much avail. The reflex arc 
behaves somewhat like cardiac muscle in responding its approximate best or not at all if the stimulus 
applied be not subliminal. 
The discontinuance ot a prolonged stimulation, especially when it is itself becoming 
inefficient, I have very often found provoke a fresh outburst of reflex activity. Head* and 
FREUsBERot have pointed out the same thing. I have seen it with faradic and with mechanical 
stimuli. After stretching a muscle from its tendon steadily and then suddenly relaxing it, the 
relaxation often causes a sudden fresh outburst of movement, a terminal discharge. 
In the Dog, soon after the performance of transection, vigorous reflex movements can be 
easily obtained ; especially in the hind limbs and tail ; these have been known and their vigour 
and variety appreciated since the papers by Marshall HalLjJ Longet,§ Brachet,|| Cayrade,^ 
GoLTZ** and Freusberg, and especially by the papers of the two last-named observers. From my 
account above given of the Monkey it will be seen, therefore, that there exists a difference 
between the condition of Monkey and of Cat and Dog in regard to reflex play in the spinal cord 
after spinal transection. To meet so great a physiological contrast between these two Mammalian 
types is surprising : the difference is distinctly great. I do not, however, believe it a really 
profound difference ; it is, I think I shall show, quantitative rather than qualitative. But it is 
nevertheless great and significant. One may almost say the Dog in this respect seems to differ 
less from the Frog than does the Macaque from the Dog, although the morphological gap between 
the two latter is so much less than between the former. In the Dog and Cat the spinal reflex 
movements are more forcible, more prolonged, more readily obtained, and less easily exhausted by 
fatigue. In the Cat and Dog it is not unusual to see the hindquarters raise themselves reflexly — 
with superficial similitude to willed movement — from the sitting to the standing posture ; this 
powerful reflex, described by Goltz, often occurs when the animal moves on being encouraged to 
stand up. In the Monkey, on the other hand, the hind limbs hang helpless, with a lethargy 
comparable to deep stupor. The few feeble abortive movements above described are difficult to 
arouse, and sometimes not elicitable at all. It might, perhaps, have been anticipated that in the 
Monkey, with its wealth of range and scope of limb movement, compared with which the hind 
limbs of the dog are little more than props, the reflex spmal machinery would have exhibited 
conformably a more multiform and surpassing co-ordination than in the Cat and Dog. * Shock ' 
once over, spinal reflexes might have been expected more various than those of other animals. 
Such a supposition is dispelled by actual experiment, as far as all cutaneous reflexes are concerned, 
although it is true that the variety of homonymous reflex about the knee of the Monkey appears 
slightly greater than at knee m the other species. 
On the other hand the difference between the variety and even the extent of the spinal 
reflexes obtainable from Cat and Dog on the one part and from Macacus on the other, is much 
* 'Journ. of Physiology,' vol. lo, p. i, 18S9. || ' Recherches experim. sur les Fonctions ties System. 
t Pfliiger's 'Archiv,' vol. 9, p. 372, 1S74. Nerveux ganglion,' Paris, 1839. 
\ ' Memoirs on the Nervous System.' London, ^1" ' Le Mouvement Reflexe. These pour le doct. 
1837-1852. 4to, London. en med.' Paris, 1864. 
^ 'Traite de Physiol.,' vol. 2, p. 241. »* PHiiger's 'Archiv,' vol. 8, p. 460, 1873. 
