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EXPERIMENTAL PHARMACOLOGY 



detect any movement inside these vessels? The larger 

 ones show a motion resembling that of a rapidly moving 

 belt. Seek out some very fine vessels and watch for move- 

 ments of the corpuscles. Can you distinguish individual 

 corpuscles in these finer vessels'? Find a place where a 



Fig. 163. Electric ophthalmoscope. The small (replaceable) battery is concealed in the 



handle of the instrument. 



very small vessel divides. Watch the movements of the 

 corpuscles as they strike against the walls of the vessel at 

 the point of division. Can you see this in the human eye? 

 Now carefully observe the rate and appearance of the 

 corpuscle flow in some easily observed (very smalt) ves- 



