2502 Journal of Applied Microscopy 



remove any excess of water either absorb it with clean filter or white blotting 

 paper, which should be placed on the slide in contact with the water, hut not upon 

 the cover, and as the water is absorbed tilt the slide so that the excess of water 

 will flow around the cover to the absorbent paper. Or, as small pipettes, or 

 medicine droppers, with rubber bulbs are, or ought always to be, on the work- 

 ing table, they may be used as successfully and quickly as absorbent paper. 

 Place the point of a fine pipette in the water at the edge of the cover-glass and 

 tilt the slide slowly toward the pipette as the water is being drawn up. 



If the objects to be mounted are so thick and delicate as to be crushed 

 between the slide and cover by the pressure of the latter, the cover is to be sup- 

 ported by a bit of thread, broken cover-glass, or paper. 



If the specimen dries out to such an extent that more water is needed, it is 

 not necessary to remove the slide from the stage. With a pipette place a small 

 drop of water near the edge of the cover and in contact with the water under the 

 cover, and it will run in. Chemical tests, e. g., the iodine test for starch, may be 

 applied in this way, so that an entire class may see the inflowing chemical and 

 the reaction it produces. 



Actively motile diatoms may be seen to move in all directions, including ver- 

 tically upward against the force of gravity, when mounted and projected as here 

 described. Oscillaria and volvox globator exhibit their characteristic motions. 



Special method for mounting paramaciuin and similar active and free sivitnming 

 species of microscopic size. 



While chloretone, as indicated in articles VIII to XIV, offers the best method 

 for controlling the voluntary activities of most species of animals during labora- 

 tory study and projection experiments, certain species of infusoria, x\o\.d\Ay para- 

 mcecium, offer a peculiar resistance, the cause of which has not been fully inves- 

 tigated, to its successful use. The following method of trapping these minute 

 forms in spaces not larger than the diameter of the field of the objective used in 

 their study was devised by the writer and has worked well in ordinary class 

 work and on the projection microscope. A small piece of clean Japanese lens 

 paper is pulled carefully by its edges until it has two to four times its original 

 diameter, thus separating its fine translucent fibers into a network of almost cob- 

 web-like delicacy. Place a piece of this about the size of the cover-glass on the 

 center of a clean plate glass or selected slide and drop upon it the water con- 

 taining the organisms, and cover with a cover-glass, which is to be pressed down 

 very gently and the excess of water removed, as above directed. The animals 

 will be found entangled in the meshes or caught under the fibers in such ways 

 that their motions, changes in shape as they pass between obstacles, and their 

 structure may be readily studied. A. H. Cole. 



University of Chicago. 



