TELEOST- -BONY-FISH. 



Material. For each student a specimen of any Common 

 fish perch, sucker, pout, cunner, etc. from eight to twelve 

 inches in length. Great care should be taken that the material 

 is obtained in a perfectly fresh condition, as the viscera decay 

 rapidly. The body-cavity should be opened so as to permit 

 free access of the preservative fluid (formol, alcohol) and the 

 alimentary canal should be injected with it through the vent. 

 The arterial system should be injected with starch mass or 

 gum mass (see introduction) through the ventricle of the heart 

 and through the caudal artery. 



For the study of the brain the head of a second fish (cod's 

 heads from the market are good) should be placed in a large 

 quantity of nitric alcohol (see introduction) about a week 

 before the laboratory exercise. It should be rinsed in run- 

 ning water for two hours before dissection to remove the acid 

 from th? tissues. This decalcifying fluid will so soften the 

 bones that they may be cut readily with the knife, while the 

 nervous structures are preserved in good condition. 



The laboratory should a^o have a prepared skull of some 

 fish like a cod or perch, as well as a number of vertebrae from 

 the table. 



TOPOGRAPHY OF BODY. Distinguish in the fish, anterior 

 and posterior, a back (dor sum) and a belly (venter), and 

 right and left sides. Make out the regions: head, trunk, 

 and tail. Is there a neck? Where is the mouth? the 



vent? 



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