and Laboratory Methods. 1645 



vacuole. Make a diagram of a cell showing the position of these streams, and 

 indicate the direction of the flow by means of arrows. 



4. Treat with a drop of iodin solution after killing the cells in alcohol. 

 Make a careful drawing of the nucleus under high power showing the nucleoli. 

 What is the normal number of nucleoli for each nucleus in these cells ? Is the 

 number constant ? Are there any starch grains present stained blue by the iodin ? 



5. Why do the scales of the bulb not have chlorophyll ? 



III. Tradescantia sp. Spiderwort. 



The flowers of almost any of the wild or cultivated species of spiderwort will 

 be found suitable. Zebrina pemiula Schnizl., the wandering Jew, so common in 

 window gardens and greenhouses, will also do very well. 



1. Study the stamenhairs. With a scalpel cut off some of the epidermis of 

 a stamen filament containing some of the young hairs. Mount in water. Be 

 careful to get the hairs wet, but do not injure them. Under low power, notice 

 that the hair is made up of a chain of cells. Draw. 



2. Study a single cell under high power. Observe the position of the nucleus ; 

 the cytoplasm, filled with small granules, lining the cell wall ; and the large 

 vacuole filled with water through which granular strands of cytoplasm stretch. 



3. Study carefully the streaming motion of the cytoplasm. Are the streams 

 constant or can you see changes going on in their position ? Do some of the 

 strands disappear entirely ? Watch the position of the nucleus for some time 

 and describe its motion. Select one that is suspended in the central part of the 

 cell. Make a large, careful sketch of a cell showing the streaming to good 

 advantage. Plot all the moving streams visible by focusing up and down, and 

 indicate by means of arrows the direction of the movement. 



4. Of what use is the reddish-violet coloring matter in the cells of the 

 hairs, petals, and leaves ? John H. Schaffner. 

 Ohio State University. 



A Convenient Method for Washing, Staining, and Dehydrating 



Small Specimens. 



It has long been known that when specimens are changed from one fluid to 

 another of difiierent specific gravity and allowed to remain quiet they are soon 

 surrounded by a halo of fluid which may not mix readily with the 

 rest. This may be obviated by keeping the fluid in constant motion. f\ ^ 



In the case of washing in water, a large specimen may be put in any 

 convenient vessel and tap water turned in. In the case of small ob- 

 jects they may be placed in a tea strainer and water allowed to pour 

 through. But in case of staining small objects or dehydrating them 

 this could not be done. 



Various methods may be devised to keep the fluid in motion and 

 thus prevent the halo of concentrated solution about the specimen. 



The writer has made use of a device which proves very satisfactory. n^ x' 



It is so simple in construction that it may be readily made by any Fig. 1. 



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