ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 507 



or squirrel, and add to it a few drops of amyl nitrite and shake violently 

 for a minute or two, or until the nitrite assumes a chocolate colour. A 

 drop of this is withdrawn with a pipette, and placed on a slide, the 

 cover-glass heing applied immediately. In a few moments the methae- 

 moglohin crystals will begin to form. By sealing the edge of the cover- 

 glass, the crystals will remain unchanged a very long time. 



Preparation of Brains and other Organs.* — Prof. M. Flesch pre- 

 pares brains for permanent preservation in the dry condition in the 

 following simple manner : — 



After having been hardened in spirit, the preparations are first 

 placed in a mixture of equal parts of glycerin, alcohol, and water, 

 and afterwards into pure glycerin. To both fluids sublimate is added 

 in the proportion of 1 to 3000. Bone and cartilage may, without 

 previous hardening, be placed in the first solution and then changed to 

 the second. The time of the treatment depends on the size of the 

 object. A human brain should lie about four weeks in spirit (if placed 

 upon cotton-wool 10-12 cm. thick, it is not necessary to change the spirit, 

 nor to turn the brain so often), then for three weeks in each of the two 

 solutions. The rest of the treatment consists in removing the super- 

 fluous glycerin by placing the specimens to drain upon a layer of 

 blotting-paper supported on cotton- wool, and they are finally put up in a 

 similar way and covered over with a glass-topped cardboard case. The 

 cost of the method is small, since both solutions can be used repeatedly. 



Preparing Radulse of small species of Gastropoda.f — Mr. C. E. 

 Beecher kills the organisms by boiling or immersion in alcohol, and then 

 extracts the animals from their shells by drawing them out with a 

 mounted needle or hook, and, in the larger species the head is cut off 

 and the remainder of the animal rejected. In the minute species the 

 shell may be removed with hydrochloric acid. Either process may be 

 employed upon shells which contain the dried remains of the animals. 



The specimens are then placed in a small porcelain crucible con- 

 taining water in a sand-bath over -a Bunsen burner. After boiling a 

 short while, a small piece of caustic potash is added and the boiling 

 continued until the tissues have become disintegrated. The boiling is 

 then stopped to prevent the thin membrano upon which the lingual teeth 

 are situated from being attacked. After removal from the burner, water 

 is added, and the undissolved material allowed to precipitate. The 

 fluid is then removed by means of a pipette, or by decantation, and fresh 

 water added, and this last procedure repeated until the potash and light 

 flocculent material are eliminated. The residue is then washed in a 

 flat-bottomed dish or large watch-crystal, and the radulse removed on 

 needles to a vessel containing a small amount of water. In case the 

 radulro are very small, the material is transferred drop by drop with a 

 pipette, and examined under a 1-inch objective ; the Microscope should 

 be furnished with an erector. The radulaa are thus easily detected and 

 removed. 



A drop of strong chromic acid is added to the specimens, and in from 

 one to two minutes the teeth on the radulae are stained a light yellow or 

 amber colour. After washing out the chromic acid, the specimens are 

 dehydrated in the usual way, and after removing the alcohol with a 



* MT. Naturforsch. Gesell. Bern, 1887, pp. xiii.-xiv. 

 t Journ. New York Micr. Soc, iv. (188S) pp. 7-11. 



