172 THE MICROSCOPE. Nov. 



tetanus or of diphtheria, commencing with a minute quantity, 

 until a condition of " tolerance " is produced, which will resist 

 an ordinarily fatal inocultaion. The blood and serum of the 

 animal then contains an antitoxine which in some way, not yet 

 understood, protects it against further infection. This serum in- 

 jected into another animal, confers upon the same immunity or 

 resistance. This serum is being used, by injection with a hy- 

 podermic syringe, in cases of diphtheria, and it is reported to 

 have materially reduced the death rate in that disease. 



PRACTICAL SUGGESTIONS, 



By L. A. WILLSON, 



CLEVELAND, OHIO. 



Fresh Mounts. — Fresh mounts should be placed in trays 

 and kept horizontal until the mounting medium and the rings 

 used have hardened. Always place a dip upon or under the 

 slide, containing the name of the object. If this latter sugges- 

 tion be disregarded, it is surprising how soon the name of an 

 object can be forgotten and the mount thereby rendered useless. 



How to Obtain Foraminifera from Chalk. — The following 

 is probably an improvement on the methods usually given in 

 books. The chalk to be used must be njitive chalk, the sticks 

 of chalk used in schools is ground and prepared and will not 

 answer the purpose. Carpenters chalk is native unprepared 

 chalk. 



Boil some fragments of chalk in a strong solution of Glaubers 

 Salts (Soda Sulphate) set aside to cool and crystallize. This 

 separates the chalk into a powder, then by repeated washings 

 and settlings, the salts and the light fluffy debris are washed 

 away and perfect shells obtained in the sediment. 



Preservation of Algae. — Alga^ keep well and jjreserve their 

 color when mounted in a solution of hydrate of chloral. The 

 following is also a fine medium for this purpose. Camphorated 

 water and distilled water each 50 grammes, glacial acetic acid, 

 .5 grammes, crystallized chloride of copper and crystallized 

 nitrate of copper, of each, .2 grammes, dissolve and filter. 



Fixing Objects to a Slide. — In arranging diatoms, spicules. 



