1899] MICROSCOPICAL JOURNAL. 345 



living- amaeboid organisms, the following method, first sug- 

 gested by Certes, will be found to give satisfactory results. 

 To thirty cubic centimeters of the water containing the 

 living amoebae, add about one cubic centimetre of osmic 

 acid solution (one per cent). After settling for a few hours 

 wash the deposit, concentrate, stain, and mount in distilled 

 water containing a trace of osmic acid. 



Yeast Cultures. — To demonstrate in yeast cultures the 

 formation of alcohol as a result of the growth of the plant 

 in a sugar solution, the following method is less trouble- 

 some than the ordinary qualitative tests, and much more 

 satisfactory. To the yeast culture add a few drops of iodine 

 solution, and then enough KHO solution to destroy the color 

 of the iodine. Iodoform will be produced and can be rec- 

 ognized by its characteristic odor. 



Insect Preservation. — The proper preservation of soft- 

 bodied organisms is one of the chief difficulties that the 

 working microscopist has to contend against. The num- 

 ber of preserving media is great, but there are few of 

 them that are at once as simple and effective as that sug- 

 gested by A. E. Verrill for preserving insects in their 

 natural forms and colors. The solution consists of two- 

 and-a-half pounds of common salt and four ounces of nitre 

 dissolved in a gallon of water and filtered. The specimens 

 should be prepared for permanent preservation in this so- 

 lution by being previously immersed in a solution consist- 

 ing of a quart of the first solution and two ounces of arsen- 

 ite of potash in a gallon of water. 



Sponges. — To kill sponges extended, the specimen is 

 placed in a glass jar filled with water, and the following so- 

 lution is added drop by drop at intervals of one minute: — 

 Methyl alcohol, ten parts; salt water,ninety parts; natrium 

 chloride, six-tenths of a part. If the specimen does not 

 retract after forty-five minutes, pour some hot sublimate 

 on quickly. To preserve specimens for sections, put them 

 in one per cent osmic acid for two minutes and then suc- 

 cessively in five, ten, twenty, thirty per cent alcohol up to 

 ninety per cent, harden in absolute alcohol and imbed in 

 paraffin, stain with borax carmine and haematoxylin. 



