No. 031] CONGENITAL PALSY IN GUINEA-PIGS 137 



time of birth rather than of being contracted at time of 

 birth, which is the connotation sometimes implied in rela- 

 tion to certain infectious diseases. The word palsy is 

 used in the general sense to indicate the broad similarity 

 of the condition in the guinea-pigs to trembling palsy in 

 man. The term is intended to be a neutral one with no 

 implications as to the ultimate cause of the disturbance. 

 The condition perhaps in some ways more closely resem- 

 bles tetany as manifested in mammals below man, but this 

 term has been avoided as having possibly too specific an 

 implication. 



There is considerable variation in the degree to which 

 different individuals are affected. In most cases the vic- 

 tim when discovered shortly after birth is lying on its 

 side slowly moving the legs, twisting the body and lifting 

 the head as if in a vain endeavor to get on its feet. The 

 movement of the fore part of the body, head and forelegs 

 is much more pronounced than that of the hind quarters 

 and hind legs. Some individuals if placed gently on their 

 feet are able to stand, though usually in a strained tense 

 attitude. The difference between this and the normal 

 position may be observed in Fig. 1, ? 1089.1 being a pal- 

 sied individual, while the others are its normal brother 

 and sisters. The photograph is taken from directly 

 above. The affected individual has the feet somewhat 

 spread and the body slightly contorted, while the others 

 are in natural easy attitudes. 



If left quietly to itself after being placed on its feet the 

 animal usually stands unsteadily for a few moments and 

 then when it starts to walk falls on its side, with charac- 

 teristic movements of the legs to be described presently. 

 Some animals are so little affected at birth that they are 

 able with effort to gain their feet themselves, and to walk 

 about in a clumsy, jerky, paralytic fashion. They expe- 

 rience the most difficulty in the control of the hind legs, 

 which appear to be in a hypertonic state and are com- 

 monly moved more in a hopping fashion than in steps.^ A 

 rough classification of 51 palsied animals soon after birth 

 gives the following: 14 unable to rise and unable to stand 



