PHANEROGAMIC LABORATORY STUDIES 247 



rise of temperature found in this experiment is the direct result of the 

 respiratory activity (oxidation) detected in Experiment 2. This ex- 

 periment also is suitable for a group of three or four students. 



Exercise IV. For pupils in groups. Of course this exercise may 

 be extended somewhat, at the option of the teacher perhaps as 

 supplementary work for fast working and interested individuals. It 

 is likely that several different temperatures may be obtained in differ- 

 ent parts of the building. And if steam heat is used, it may be 

 possible to arrange matters so that minimum, maximum, and optimum 

 temperatures of germination can be approximately determined. 



Exercise V. For the facts and theory of the response of growing 

 parts to various external stimuli, see the text-books under Geotropism, 

 Heliotropism, etc.; Goodale, pp. 392-396, Strasburger's "Text-book of 

 Botany " (Porter), 1898, pp. 251 et seq. 



Exercise VI. Experiment 6. For an account of the green coloring 

 matter (chlorophyll) see Goodale, pp. 286 et seq. It would be inter- 

 esting to compare the behavior of Pine seedlings with those of com- 

 mon garden plants in respect to the development of chlorophyll in 

 darkness. It may take a month to get the pine started. 



When the results of the experiments on germination are in, the 

 teacher will, of course, discuss the teachings of the experiments with 

 the class, making them points of departure for the giving of a greater 

 or less amount of related information. The time taken by the seeds 

 mentioned to germinate and come to the various desired stages of 

 development will depend on the temperature of the room. The fol- 

 lowing data will give some idea of the time required. Squash, 1 inch 

 deep, came up in 6 days in a warmish place. Onion, in. deep, was 

 looping up well in 9 days in warmth. White Lupine, 1^ in. deep, came 

 up in 7 days in a rather cool place. The plants were erect and had 

 spread leaves in 14 days. Pea, 1 in. deep, was coming up freely in 6 

 days. Morning Glory was up and had cotyledons spread in 5 days. 

 The seeds may be sown at intervals during two weeks or so in boxes 

 of soil or wet sphagnum. Several pots may be sown to show the 

 manner in which the young plants come out of the ground. 



Supplementary Topics. i. This will require the compound micro- 

 scope. Spiranthes cernua, or Maiden's Tress, is markedly poly- 

 embryonic. The embryos are produced without fertilization. (See 

 Rhodora, December, 1900.) The embryos are seen at a glance, the seed- 

 coats being transparent. Spiranthes cernua blooms in September and 

 October. Mount seeds first in alcohol. 2. The Larch and Spruce 

 seeds named germinate readily in 10 or 12 days. 



Chapter III. Discuss the subject of winter buds. Some such line 

 of thought as the following is suggested : Why do trees like the 

 Maple, Elm, etc., lose their leaves in winter? (Two reasons, at least. 

 For xerophytic conditions in winter, see p. 65.) When does preparation 



