196 ANSWEMS TO PRACTICAL QUESTIONS * 



27. How many rows of hairs are there in the eyebrows ? 



The eyelashes, or cilia, consist of two, and opposite the 

 middle of the eyelid, of three rows of finely-curved hairs 

 those of the upper lid being more numerous, thicker, 

 and longer than those of the lower lid. " Those of the 

 upper lid are curved upward, those of the lower lid are 

 curved downward ; and when the lids are brought near 

 together, these two ranges of hairs stand like so many 

 crossed sabres, or a kind of chevaux-de-frise, guarding 

 the entrance to the eye." DALTON'S Physiology, p. 330. 



28. Do all nations have eyes of the same shape ? 



No. Witness the almond-shaped eyes of the Chinese. 

 " The greater or less extent of the opening of the lids 

 makes the eye appear larger or smaller ; the conforma- 

 tion of the palpebral muscles and the tarsal cartilages 

 gives to the eye an elongated and languishing form as in 

 the East, or round and bold as among the Occidentals ; 

 but the dimensions and form of the globe are the same in 

 all countries and in all individuals." Wonders of the 

 Human Body. 



29. Why does snuff-taking cause a flow of tears ? 

 Because of the action of the sympathetic system. 



30. Why does a fall cause one to " see stars ?"* 



Whenever a nerve is excited in any way, it gives rise 

 to the sensation peculiar to the organ with which it com- 



* u On the occasion of a remarkable trial in Germany, it was claimed by a 

 person who had been severely assaulted on a very dark night, that the flashes 

 of light caused by repeated blows upon the head enabled him to see with 

 sufficient distinctness to recognize his assailant. But the evidence of scien- 

 tific men entirely refuted this claim, by pronouncing that the eye, under the 

 circumstances named, was incapacitated for vision." HUTCHISON. 



