THE NATURALIST, 



DECi:MBER, 18 3 2. 



THE MICROSCOPE. 



* NO. V. 



THE CIRCULATION OF THE BLOOD. 



In order to view the blood circulating through its vessels, we 

 must procure animals, the skins of which are transparent, and no 

 object is better calculated for this purpose than the small tadpole. 

 The circulation of the blood in this little animal is a most magnif- 

 icent spectacle. In order to view it to advantage with the mi- 

 croscope, place a piece of window glass about two inches by one 

 upon the stage; upon this the animal is to be placed without any 

 further preparation.* The tail will now lie flat, and, being very 

 transparent, the innumerable channels contained in it will be per- 

 fectly visible, within which the blood, consisting of globules sus- 

 pended in serum, will be perceived coursing with extreme rapid- 

 ity in all possible directions. 



Along one side of the longitudinal tapering substance in the 

 centre of the tail, a main conduit proceeds to the extremity there- 

 of, returning towards the body, at a very small distance from the 

 salient part, and in a parallel direction; from this, branches pro- 



*■ When tlie animal is first placed upon the glass, it usually wriggles about, but soon 

 becomes quiet, and nirnains so for some time. Should it repeat its motion, there will 

 always be sufficient intervals of quiet fo.-- readjustment and examination wliich makes 

 this mode of submitting to the microscope preferable to any attempt to confine it. A 

 small quantity of the water should be placed upon the glass ; the power, No, 2, is the 

 most suitable. 



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