43 COLLECTION AND PRESERVATION OF MATERIAL. 



fully tied up in pieces of bibulous paper, with the labels written in 

 India ink or pencil, inside. In this way, many different things can 

 be kept in the same jar and thus economize room and solutions. 

 If the material is to be preserved in thick collodion, the stopper of 

 the vessel in which it is placed should make the bottle air tight and 

 should also be held in place in some way, otherwise the evapora- 

 tion of the ether may force it out and ruin the material by the 

 hardening of the collodion. If it is desired that the tissue be kept 

 on blocks in alcohol any great length of time, in order that it may 

 be ready for use at once, hard rubber rods sawed into convenient 

 lengths of about 2 c.m. may be substituted for the cork. As the 

 alcohol does not effect the rods, tissue can be kept in this way any 

 length of time without deterioration. The rubber rods can be 

 obtained of the Educational Supply Co., Boston. 



Blocks of hard wood have also been suggested for the same 

 purpose. 



In collecting material to preserve for class-room work, much 

 care should be taken to prevent confusion of labels, etc., and all 

 important data should be included with the notes on each study. 



