EXAMPLE 2 



Preparation of a Wholemount of Pectinatella Stained 

 in Grenacher s Alcoholic Borax Carmine 



Although this description applies to the animal named, it may be used 

 equally well for any other fresh-water bryozoan or, as a matter of fact, for 

 any small invertebrate of about the same size and consistency. Pectinatella 

 has been chosen only for the reason that it has the habit of turning up 

 on the walls of the aquaria in the author's laboratory. Profitable hunting 

 grounds, if they have to be sought, are the undersides of the leaves of 

 large water plants and the surfaces of branches of trees that have fallen 

 into the water but have not yet had time to decay. An old trick of Euro- 

 pean collectors was to lower a length of rope into a pond in which 

 Bryozoa were known to occur and to leave it there for the summer. It 

 was astonishing how frequently, when these ropes were pulled up again 

 in the fall, they were found to be covered with colonies of Bryozoa. 



However the Bryozoa are obtained, it is necessary first that they be 

 narcotized. The material on which they are living is cut up and placed 

 on the bottom of a finger bowl of aquarium or pond water. Distilled water 

 and tap water are lethal to these forms. There should not be so many 

 specimens that they touch each other on the bottom of the finger bowl, 

 and the finger bowl itself should be completely filled with water. The 

 fresh-water Bryozoa are a little sensitive to heat and may not respond 

 well to the high temperatures found in some laboratories. In this case it 

 is well to put the finger bowl containing the specimens in an icebox or 

 electric refrigerator, preferably one held at about 10° C, and to leave 

 it there overnight. Then the specimens may be brought out and narcotized 

 before they have time to suffer from the increasing temperature. 



The author prefers to use menthol, which is both cheap and easy to 

 obtain. The menthol is sprinkled on the top of the water in the specimen 

 jar. For an ordinary finger bowl, about 1 g of menthol will be sufficient. 

 There is no means of foretelling how long it will take the specimens to 

 become narcotized; therefore, they should be observed at intervals until 

 they no longer are seen to be contracting. However, this may not be due 



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