22 



EVENINGS AT THE MICROSCOPE 



two rows, that allow the rays of light to be transmitted 

 through their central parts. 



As we trace the hair upward, by moving the stage of 

 the microscope, by and by it swells and rapidly increases 

 in thickness; the imbrications are scarcely perceptible; 

 while the pith-cells have greatly augmented in number 

 and in breadth. These are arranged in confused, close-set, 

 transverse rows, and are nearly opaque. 



Still tracing up the same hair, as we approach the tip, 



HAIR OF SABLE. 



HAIR OF MOUSE. 



the bark and fibrous part become very thin; the cells are 

 fewer and fewer till they cease altogether, and a long 

 slender point, of a clear yellow tinge, without cells, pre- 

 sents transverse wavy lines of imbrication scarcely pro- 

 jecting. 



The hair of the common Mouse is a pretty and interest- 

 ing object. In the larger specimens the fibrous portion 

 is reduced almost to nothing. The imbrications project 

 very little, but careful observation reveals slanting lines 

 proceeding from the "teeth"; which, show that the whole 



