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THE AM ERIC AX XATUBAL1ST [Vol. LIV 



when placed on their feet ; 18 able to stand but unable to 

 walk; 5 able to walk when placed on their feet but unable 

 to arise unaided; and 14 able to get up and to walk. It 

 should be recalled that in all cases the symptoms grow 

 progressively worse, leading to the most severe condi- 

 tions, and to death in a week or two at most. 



Breathing appears to be normal, as is also control of 

 the muscles of the jaws and throat, for the less affected 

 animals sometimes eat solid food, and those that are able 

 to walk may suckle the mothers. Sueli individuals increase 

 in weight for a time as rapidly as normal young, but with 

 the progress of the disease they become unable to obtain 

 nourishment, and consequently decline. We are unable 

 to state at present whether death is attributable finally to 

 starvation, or whether it is a direct sequel of the disease. 



The most striking phenomenon in connection with the 

 disease is the reaction to stimuli, particularly to auditory 

 stimuli. This may be best observed in animals that can 

 stand when placed on their feet but are able to walk only 

 with great difficulty, if at all. If such an animal is placed 

 on its feet and a sharp sound is then made, such as clap- 

 ping the hands, snapping the lingers, or squeaking with 

 the lips, the reaction is definite and immediate — the sub- 

 ject jumps upward and forward, due to a sudden stiffen- 

 ing, particularly of the hind legs, then falls on its side, 

 the whole body shaking to some extent, but the legs ex- 

 hibiting strong clonic spasms. To the same stimulus nor- 

 mal individuals give merely a slight start, and then sit 

 unconcernedly as before. This result is clearly shown in 

 Fig. 2, which depicts the same litter as Fig. 1, but follow- 

 ing a stimulus which has thrown the affected individual 

 into a spasm as described. Fig. 3 is a short time-exposure 

 of an animal in a spasm lying on its side. The photo- 

 graph shows clearly the movement of the feet. 



Visual stimuli have relatively little effect in producing 

 the above-mentioned reaction. Even if the hand is 

 brought rapidly down to near the animal's eyes it seldom 

 responds. The same is true for mechanical stimuli, the 

 reaction occurring only if the stimulation is severe. Af- 



