488 STUDIES IN ADVANCED PHYSIOLOGY. 



judgment of weights. Of objects that have the same weight 

 those that are larger seem lighter. Again, an object seems 

 lighter when it is elevated with both hands, instead of one. 

 No doubt we judge of the weight of objects by noticing the 

 amount of effort necessary to bring about the required 

 motion. Such a sensation is really not one of the muscles, 

 it is a measurement of the brain's own activity in the inten- 

 sity of its motor impulses. This does not preclude the pos- 

 sibility that sensory nerves distributed in among the muscles 

 may take part in giving us our sensations of passive move- 

 ments. Not only are we able to perceive motions which we 

 voluntarily make, but we are also able to perceive passive 

 movements. To be suddenly moved forward, to have this 

 motion checked or to be turned right and left, or to have the 

 rapidity of the motion varied is at once a matter of knowl- 

 edge. It seems very probable, however, that this knowl- 

 edge of passive movements is in no sense connected with 

 the muscles, or even due to the inertia of the body or its 

 centrifugal actions, but that it is due entirely, or at least 

 largely, to changes which are occasioned by lymph move- 

 ments in the semi-circular canals of the ear, in connection 

 with which a detailed explanation of this matter is given. 



THE SENSE OF TASTE. 



The sense of taste is located in certain parts of the mucous 

 membrane of the mouth, especially on the mucous membrane 

 covering the tongue. The under side of the tongu,e is not 

 sensitive to taste. The same is true of the lips and gums 

 and the cheek. It is asserted, however, that in small chil- 

 dren these parts are able to give sensations of taste. The 

 exact location of these taste areas may be easily established 

 by taking a sapid powder and applying it point for point 

 over these areas. A liquid would not be satisfactory for 

 this purpose, as it would naturally spread to the neighboring 

 areas. The sense of taste may also be anatomically located 

 by the presence of taste bulbs. These taste bulbs, dis- 

 covered by Loven and Schwalbe in 1867, are small barrel- 



