Decembek 19, 1919] 



SCIENCE 



555 



demise in Lilium Martagon, and the last 

 " slide " is " drawn." 



Is this a caricature? No more so than 

 many such a course is a caricature of reality 

 in the plant world. The question is, does it 

 pay, with the limited time usually available, 

 to sketch hastily through a syncopated genetic 

 series in secondary school work. The pri- 

 mary object in following such a series 

 through, is to get before the student a picture 

 of the upgrowth of the sporophyte form, 

 which is the final stage in morphogenetic evo- 

 lution in plants, and through the facts in re- 

 production, throw light upon the evolutionary 

 relationship of the various phyla. 



To this end, beginning students who have 

 usually observed little with their eyes, have 

 to be armed at the very outset with the 

 dubious weapon of the compound microscope, 

 and their first weeks in botany are consecu- 

 tively devoted to an examination and study, 

 almost entirely through the microscope, of 

 organisms that the most favorably disposed 

 among them are hardly prepared to appreciate 

 as plants. From the pedagogical standpoint 

 this is a weak approach. If however, instead 

 of the groups of the Thallophytes, and the 

 succeeding members of the evolutionary series, 

 the seed plants are made from the outset the 

 center of gravity of the teaching, the interest 

 and sympathy of the students is more easily 

 impounded. If this method is followed, it is 

 desirable, instead of beginning with a study 

 of seeds and seedlings and so on, to com- 

 mence with a complete life-cycle exercise 

 covering the entire life histoi-y of the species, 

 from the seed on to maturity and seed repro- 

 duction. This can be done by means of a 

 serial succession of plantings made in ad- 

 vance, whereby the student gets at once at a 

 given laboratory period, an immediate present 

 view of all the stages through which the plant 

 has had to pass. Lima beans, for example, 

 handled in this way, will give satisfaction, 

 and, in the final stages, will furnish a com- 

 plete series in the plant's reproduction, from 

 unfertilized flowers on to well-grown seed 

 pods upon the same plant. All the morpho- 

 logical details of structure of all the different 

 organs may be worked out at once upon 



such a plant, and many species may be intro- 

 duced in series in the same manner for com- 

 parative study of types of development. The 

 morphology however, it ought to be empha- 

 sized, should be accompanied step by step, by 

 experiments in the physiological behavior of 

 the same organs. Osmosis experiments should 

 accompany the study of roots and root-hairs, 

 and not be postponed to some future exercise 

 in physiology Transpiration and photosyn- 

 thesis experiments should be conducted sim- 

 ultaneously with the study of the leaves as 

 such. Conduction should be studied experi- 

 mentally, at the same time with the study 

 of the structure of stems. The rate of 

 growth of stems and roots, and of the floral 

 organs before and after fertilization, should 

 be determined while the students are engaged 

 at the same time upon the morphology of 

 those structures. 



It is a useful and practical thing, when 

 dealing with the structure of leaves, for ex- 

 ample, to take plants in which there is a 

 considerable deposition of reserve food, such 

 as corn, potato, sweet potato, etc. ; in warmer 

 regions, taro, sugar cane and banana, and 

 have the pupils determine for the entire plant, 

 the total percentage amount of combustible 

 dry matter, taking the storage regions sep- 

 arately as such. By separately determining 

 the total percentage amount of water, dry 

 matter and ash, the work of the plant as a 

 machine in the manufacture of carbohydrates 

 can be plainly seen. If the area of the leaves 

 is now measured, the number of grams of 

 carbohydrates produced per unit of leaf sur- 

 face can be calculated, and this in turn can be 

 converted into terms of energy in calories. If 

 such an exercise as this, together with field 

 work in leaf ecology, accompanies the study of 

 palisade cells, stomata and conduction tissues 

 in leaves, the latter will be seen in the light of 

 functioning organs, and not as static struc- 

 tures. There seems to be no disputing the 

 fact that the study of the structure of organs 

 will be vitalized, by experimental work along- 

 side at the same time upon their functions. 

 It is correspondingly useful, for example, 

 while engaged in the study of the structures 

 of reproduction, to have the pupils demon- 



