38 PLANT PHYSIOLOGY. 



from cuttings six weeks before needed. These plants are easily grown 

 and most useful for many purposes. They should be always in stock. 



Sensitive plants should be grown, at a temperature of about 70, in a 

 sandy soil from seed planted five months before they are needed. 



Coleus is best propagated from cuttings in a warm house five weeks 

 before needed. 



Impatiens Sultani, a useful plant, grown from seed needs two to three 

 months to bring it into 4-inch pots. 



Melothria punctata, used for its tendrils, is kept propagated by cut- 

 tings and can be rooted and brought into 3-inch pots in five to six weeks. 

 Echinocystis is also excellent, for outdoor work. 



E. PERSONAL EFFECTS OF EACH STUDENT. 



Note-book of 200 pages, as described on page 14. 

 Colored pencils. 



Liquid India ink and fine mapping-pen. 

 Towel, sponge. 



5. MANIPULATION. 



Much of the manipulation required is simply that learned 

 in every elementary course in Chemistry, but for completeness 

 the most important processes will here be described. Special 

 methods used only once or twice in the course will be described 

 under the particular experiments. 



To Cut Glass Tubing. If under about i cm. diameter, file a shallow 

 nick at spot to be broken ; turn this from you, and, grasping the tube 

 firmly with thumbs and forefingers each side of the nick, pull apart 

 the two ends and bend the nick sharply away from you, when the tube will 

 break across. If slightly over i cm. diameter, a deeper nick will allow 

 it to be broken in this way ; but if much over, or if a vial or a bottle is to 

 be broken, the following method is efficient. File a nick across where 

 the desired line of separation is, tapering the nick each way. Wrap 

 around the tube two long strips of wet filter-paper parallel with the de- 

 sired line of separation, each a mm. from it in thin tubing and farther in 

 thick. Hold the nick in the hottest part of a Bunsen flame until it cracks 

 cleanly across. Or, file a groove all around the place to be broken, mak- 

 ing it deeper in one part. Hold this spot in the hottest part of a line 

 blowpipe flame, when the glass will crack along the groove. A very hot 

 iron led along the path to be broken is said to be effective. For large 

 glass tubing a very efficient special cutter may be purchased. 



