1886 



Journal of Applied Microscopy 



secure handsome preparations, but it will be repaid by the improved appearance 

 of the cases containing the preparations. 



The preparations here described and figured belong to the botanical museum 

 at the University of Michigan, and are used in various ways in class work 

 in botany. 



The method of manufacture is briefly as follows : The plant material is 

 selected with a view to illustrating some particular fact or principle ; it 

 should be transported to the laboratory, allowing as little wilting as possible, 

 especial care should also be taken not to bruise any part of the plant, as it 

 often causes black spots. The material is thoroughly washed, using a soft brush 

 if necessary to remove all adhering particles of earth, etc. After washing, the 

 plants should be placed in a jar of two per cent, formalin for two or three days, 



Fig. 3. — Pleurotus petaloides. 



Fig. 4. — Helianllius tuberosus. Develop 

 ment of tubers. 



in order to kill them and extract such of the coloring matter and juices as will 

 come out readily ; if this is not done the fluid in the permanent preparations often 

 becomes cloudy. 



Another method of killing which best preserves green colors, is by the use of 

 a weak solution of copper salts. Several modifications of this method are in use 

 in different museums: the following, ^ which is not original with the writer, has 

 proven very satisfactory : The air is removed from the intercellular spaces of 

 the plants by immersion in 90 per cent, alcohol or by immersing the plants in boiled 

 water and placing them under the receiver of an air pump. When as much air 

 as possible has been removed, the specimens are placed in a 5 per cent, glycerine 



1 Woods, Alfred F., Bot. Gaz. 24 : p. 206. 



