GEANTIA 75 



preferably alcoholic, as these are tougher, should be di- 

 vided into halves longitudinally with the razor, and 

 still others cut transversely. If the conveniences neces- 

 sary for ceUoidin or paraffine embedding and the micro- 

 tome are not at hand, fair sections may, after a little 

 practice, be made with the razor from well -hardened 

 alcoholic material. Such sections may be stained in 

 Delafield's hsematoxylin, borax carmine, or, if decalci- 

 fied, in acetic acid carmine, and then mounted in water, 

 fifty per cent, glycerine, or Canada balsam after passing 

 through the preliminary treatment required by the dif- 

 ferent fluids. 



Spicules may be isolated for examination free from 

 the tissues, by placing specimens in a test-tube or watch- 

 glass containing potash, boiling for a few minutes, dur- 

 ing which the fleshy parts of the body dissolve, allowing 

 the sediment to settle, pouring off the fluid, and rinsing 

 the sediment several times with fresh water, being care- 

 ful each time to allow the sediment to settle before pour- 

 ing off the water. A drop of the sediment may then be 

 taken out of the test-tube with a pipette and placed on 

 the slide for examination. 



MOEPHOLOGT 



With an entire specimen notice : 



a. Shape. — "What is the usual shape of a single sponge ? 

 Is it a symmetrical form ? Can you distinguish 

 an upper and a lower end ? How ? Is the sponge 

 attached to anything, or is it free to move about? 

 If the former, to what is it attached ? Is its shape 

 at aU modified for this purpose ? Do you find any 

 decided variations from the general shape ? Can 

 you explain them ? Are all of your specimens 



