366 SERGIUS MORGULIS 



ness, for example, which has been developed by Munk on the basis 

 of his extirpation experiments of the occipital and frontal lobes 

 must be discarded as meaningless. Munk's dogs, whose brains 

 were deprived of the visual centre, could neither distinguish 

 one thing from another nor recognize their owner, but they 

 invariably avoided obstacles in their way. The psychological 

 interpretation that animals with such brain defects " can see " 

 but ' cannot understand ' is no longer necessary. With the 

 destruction of the central and most delicate portion of the visual 

 analyser, its power to differentiate light stimuli is much restricted. 

 Depending upon the degree of injury, the power to analyze the 

 very complex visual factors may be partially or entirely lost. 

 The dog which avoids an obstacle but does not recognize its 

 master has retained the more primitive and more generalized 

 function of the visual analyzer to differentiate between intensi- 

 ties of light but it has lost the finesse of the mechanism necessary 

 to differentiate form, color, etc. The study of conditioned 

 salivary reflexes substantiates this view. With a slight injury 

 to the occipital lobe it was possible to form conditioned reflexes 

 to such factors as movement, form, etc. With a more serious 

 encroachment upon the integrity of this portion of the brain the 

 grading between light and shadow alone could be made a con- 

 ditioned stimulus for the salivary gland. 



In this connection it is interesting to review a series of experi- 

 ments with a dog whose central portion of the tactile analyser 

 has been removed. Prior to the operation on the brain several 

 conditioned reflexes were worked out with this animal to 

 both tactile (thermal and mechanical) and auditory stimuli. 

 The behavior of this operated dog was peculiar in one respect 

 only. When placed anywhere in the room it would remain in 

 the same position indefinitely without ever moving a limb. Its 

 legs seemed to be paralyzed and fastened to the underground, 

 but other parts of the body behaved normally. All conditioned 

 salivary reflexes to irritation of the skin were lost. The lower 

 reflexes of the spinal cord, such, for instance, as the defensive 

 reflex, still persisted and every time the dog was petted, though 

 no ill intentions were revealed, it scowled, barked and attempted 

 to bite. This happened even if food was offered at the same time 

 and is due to the absence of the higher centre of the tactile 

 analyzer. The behavior of the dog among solid objects was very 



