DISSECTING. 117 



moisture removed from the surface, and, of course, it should 

 not be placed above the middle line in the wax. 



At the close of the day's work the specimen should be re- 

 moved from the tank and placed in alcohol, while the tank 

 itself should be placed wrong side up to drain. 



Below is given a very brief account of the methods of 

 studying the gross anatomy of a number of types ; all descrip- 

 tions of the organs being intentionally omitted. As the 

 student proceeds, he should make drawings as well as notes 

 of his work and should endeavor to rely as much on himself 

 and as little on text books and instructors as possible. 



Protozoa can only be studied with the microscope. 



Sponges are best studied by cutting sections and examining 

 them under the microscope. The various structures and ar- 

 rangements of parts can then be made out more or less 

 clearly, and the eggs and embryoj in \arious stages of de- 

 velopment can frequently be seen. To study the spicules, 

 the specimen should be macerated in water, then picked to 

 pieces with needles and examined under the microscope. 



Sea Anemones are dissected from the side, when the 

 genitalia, mesenteries and digestive portions are seen. By 

 freezing and cutting transverse sections, the relations of the 

 mesenteries to the alimentary canal are made out. The 

 various cell layers should be studied in stained microscopic 

 sections and the lassoo cells should be looked for. 



Starfish should have the upper surface of the arms removed, 

 taking care that the portion around the madreporic body be 

 left uninjured until it becomes necessary to cut it away. Sea 

 Urchins may be divided into two halves by a horizontal plane, 



