BY DR. MICHAEL FOSTER. 415 



of a frog possessing the spinal cord only. The head is well 

 raised on the fore limbs. 



Respiration goes on in an almost normal manner. 



If left to itself, and protected from all external stimuli, the 

 animal will remain perfectly motionless. For some little time 

 after the operation has been performed, movements apparently 

 voluntary, that is, occurring without any obvious cause, are 

 frequently witnessed. These, however, generally cease after a 

 little while, and if the animal lives long enough for the wound 

 to heal, entirely disappear. 



The animal will not feed of itself. Flies, worms, etc., may 

 be placed close to it, and even introduced between the teeth, 

 without any notice being taken of them. If, however, the 

 mouth be opened and a morsel be introduced into the pharynx, 

 it is swallowed. In this way the animal may be kept alive for 

 an indefinite period, being fed on pieces of worm or flesh ; frog's 

 flesh does very well ; care must be taken not to introduce too 

 large pieces, and not to feed too often. 



If the skin round the anus be pinched, the animal does 

 more than simply kick out its hind legs : it leaps forward, often 

 repeating the leap several times, and springing forward a con- 

 siderable distance ; sometimes it crawls instead of leaping, and 

 not unfrequently does both. If placed on its back, it imme- 

 diately turns over again to its normal position. This it does 

 instantly and with vigor. It has to be held down forcibly in 

 order to keep it on its back for any length of time. 



If thrown into a basin of water, it at once begins to swim, 

 and continues swimming about with considerable energy till 

 it finds some resting-place. Having found a suitable support, 

 it crawls upon it, and assumes the normal attitude, and there 

 remains motionless until again disturbed. 



If the cerebellum be removed, all these movements and 

 habits become much impaired, much feebler, and less striking; 

 or may (with the exception of the respiratory movements) be 

 wholly absent, but it is difficult to remove the entire cerebellum 

 without injury to the medulla. Hence the share taken by each 

 organ in keeping up thete powers of executing complicated 

 movements cannot be readily ascertained. 



The above facts all point to the existence in this part of the 

 brain of some mechanism connected with the co-ordination of 

 movements. The crawling, leaping, swimming, and turning 

 over on to the belty till demand a more complex nervous 

 machinery than is needed for the purely spinal reflex actions, 

 intricate as many of these are. 



The persistence of what we have called the normal attitude 

 is very remarkable. Strictly speaking, the natural frog varies 

 its attitude constant!}', but its most common posture, the one 

 into which it naturally falls when at rest, is the one we have 



