H4 PLANT PHYSIOLOGY. 



to be recorded. Prepare a recording glass supported by a tripod as 

 shown in Fig. 29, the glass being some ten inches above the plant. 

 Prepare the slenderest glass filament (see page 39) you can, 2 cm. 

 long; place a tiny bead of black wax on one end, and slip about a 

 half cm. up the other a tiny circle of white paper with a tiny black 

 spot in the middle through the center of which passes the filament. 

 Attach this filament vertically to the side of the top of the stem 

 with shellac, bead upward. Sight through the glass plate, bringing 

 the bead and black spot into line, and, exactly on the line of sight on 

 the plate, make a mark with a very fine glass pen made by drawing 

 a glass tube to a capillary point. Chronograph ink should be used. 

 Record three or more times a day for two or three days, joining the 

 marks and marking the times. On some single warm day, record at 

 intervals of ten minutes for two or three hours. The records may 

 be traced from the glass by use of tracing-linen. 



Another, somewhat different, and more exact method of securing the 

 record is given by Stone in Botanical Gazette, 22, 262. 



Usually the points obtained in the observations are joined by straight 

 lines, but the resulting angularity conveys a very wrong impression of 

 the real nature of the movement; hence I think it better to join the 

 marks by sweeping curves of as limited radius as possible ; the result 

 will be at least as correct as the straight lines and much more true to 

 nature. 



74. Do these autonomic (in this case Circumnutation) move- 

 ments occur in connection with other growth movements? 



Answer by Experiment 43. 



EXPERIMENT 43. The bending movement made by seedlings in 

 lifting their cotyledons from the ground may be utilized in testing 

 this. Plant in a pot of earth three or four Lima beans (using several 

 in order that some one may be pretty sure to be in proper condition 

 when wanted), and when the bow of the hypocotyl of one of them 

 appears just above the ground, attach to its highest point the fila- 

 ment and circle used in the preceding experiment, and record on the 

 glass the movements during the straightening of the hypocotyl. As 

 this takes place rapidly, it is needful to record often. 



75. How widespread is the circumnutation movement, and 

 what is its fundamental significance ? 



Answer from your various sources of information. 



76. What are the other known autonomic movements? 

 Answer from your various sources of information. 



