PHANEROGAMIC LABORATORY STUDIES 251 



Use potato starch. Apply a solution of | teaspoonful diastase (drug- 

 gists or supply companies) in 1 teaspoonful water a few drops on a 

 slide. Observe, after 15 minutes, the erosion and disintegration of 

 many of the grains. 



Experiment 12. Respiration takes place in all living members of 

 the plant. (See the final chapter of the text, this book.) Experi- 

 ment 13. A Geranium (Pelargonium}, a Sunflower seedling, or a 

 Fuchsia, is easily got. The experiments on transpiration (which sub- 

 ject see in Goodale, Strasburger, and this book) are easily extended, 

 so as to test the effect of a number of conditions. (See Ganong for 

 further suggestions.) Convenient balances are the " Harvard trip 

 scales " (apparatus dealers). The sheet rubber is a grade or two 

 heavier than that used by dentists. 



Experiments 13, 14, 15, and 16 are all on the same activity of the 

 leaf, transpiration. It will be well to have only one or two prepara- 

 tions of each experiment, and have all the experiments going on at 

 once, prepared simultaneously by different groups of pupils. The 

 essential features of manipulation are seen at sight, and the results 

 are obvious, so that the whole class may take notes from apparatus 

 prepared by two or three pupils solel}^ The importance of transpira- 

 tion in drawing water from the soil, and with water the nutrient 

 soil salts, should be discussed when the results are all in. Stomatal 

 regulation may be brought up in connection with the results of Ex- 

 periments 15 and 16, in' which it is seen that the vapor escapes from 

 the under surface largely. Experiment 17. Young potted Tropae- 

 olums, a month or two old. On heliotropism, or turning occasioned 

 by light, see Goodale, p. 392, or Strasburger, p. 251. The chapter on 

 physiology, in this book, may be referred to. Experiment 18. Seed- 

 lings of Mimosa pudica may be grown to suitable size in 3 or 4 weeks. 

 Seeds from seedsmen. Oxalis seeds also from seedsmen, or plants 

 from growers. On "sleep" movements, see Goodale, p. 409, and 

 Strasburger, p. 270. The irritability of plants is a most interesting 

 subject of study. 



Exercise XXIV. Of greenhouse material, Hibiscus or Abutilon is 

 very good for all points in this exercise. Geranium (Pelargonium) 

 and German Ivy (Senecio scandens) have stipules. The veining does 

 not show so well. Of outdoor things, Apple and Quince have stipules. 

 Selections of the best leaves to illustrate types of venation, compound- 

 ing, etc., should be made in the summer, and the leaves pressed. But 

 for Exercise XXIV. fresh material is needed. 



Exercises XXVI. and XXVII. The assortment of leaves given the 

 pupil will include parallel- and net-veined examples ; and of the latter, 

 some pinnate, some palmate. Several examples of each category 

 should be provided. Let some be lobed, divided, etc., so as to suggest 

 the origin of compounding. Pinnately lobed, palmately lobed forms, 



