90 Animal Microloyy 



Water 42 c.c. 



Gelatin 6 grams 



Glycerin 50 c.c. 



Carbolic acid crystals 2 grams 



Dissolve the gelatin in the water and add the glycerin and the 

 carbolic acid. Warm for 10 or 15 minutes stirring continually 

 until the mixture is homogeneous. Do not heat above 75 C. or 

 the gelatin may be transformed into metagelatin which will not 

 harden at ordinary temperatures. Filter through fine hot flannel. 

 Use only clean gelatin of the best quality. 



A. Small Crustacea. 1. By means of a dipping-tube isolate 

 such small creatures as Cyclops, Daphnia, or Cypris. 



2. Kill by warming slowly in a drop of water on a slide. 



3. Place them in a cell of proper depth, draw off all water 

 with a pipette, and gently warm the slide. 



4. Place the bottle of glycerin-jelly into a vessel containing 

 warm water until the jelly becomes liquid, but do not let it get 

 any warmer. 



5. Fill the cell flush with the warm jelly and arrange the 

 objects in suitable positions. 



6. Breathe upon the lower surface of a clean cover-glass and 

 put it in place in the usual way. 



7. Wash away any trace of the jelly from the outside of the 

 cell and when the slide is dry run a ring of gold-size cement 

 around the edge of the cover. After this dries varnish with Bell's 

 cement. It is not an absolute necessity to seal glycerin-jelly 

 mounts, but the writer has always found it a wise precaution. 



B. Muscle of Insect. 1. Cut off the head of an insect and bisect the 

 trunk so as to expose the interior. Observe two kinds of muscular tissue, 

 that of grayish color belonging to the legs, the yellowish to the wings. 



2. Take a shred of muscle and on a dry slide carefully separate 

 pieces of muscle fiber and stretch them out, while keeping them moist 

 by breathing on them. 



3. Mount in glycerin-jelly as directed in the previous exercise. See 

 also Appendix C, IX. 



IV. MOUNTING IN BALSAM 



A. Flat Worms. -1. Obtain specimens of Planaria from the 

 under surface of flat rocks in the edge of streams (see Appendix 

 D, "Planaria"). 



