622 



NATURE 



[October 23, 1890 



On the other hand, the roots are fairly typical in structure, 

 and introduce the student to the ideas of the root-cap, apical 

 cell, radial bundles, and axial vascular cord. The stem, at 

 least, shows how the vascular bundles havedefiniteness and con- 

 tinuity of course, in axis and appendages, and these bundles are 

 so large and isolated that an introduction to the notion of their 

 development from embryonic tissue is at least attainable ; more- 

 over, the spiral vessels, scalariform tracheides, sieve-tubes, and 

 packing-cells suffice very well — though, of course, in different 

 degrees — to introduce the elements of the xylem and phloem, 

 and I regard it as an advantage to defer the complex idea of 

 cambium. 



Elementary notions of other items of complexity appear in the 

 extra fascicular strands of sclerenchyma, while protective hairs, 

 reserve-starch, continuity of leaves and axis, and their origin 

 from the meristem, &c., all serve as foundation stones if pro- 

 perly demonstrated and discussed by the teacher. 



But it is the sporophyll on the one hand, and the prothallus on 

 the other, which make the fern so supremely useful as a type. No 

 conceptions in the morphology of plants have been more fruitful 

 than these, and it is of the highest importance that the student 

 really sees and examines these and their accessories for himself. 



The beauty of the fern sporophyll as a type for demonstration 

 lies in its being so evidently a leaf, in the sense understood at 

 once by the beginner ; then the sorus, sporangium, and spore 

 are evident and easily examined, and even the very useful ideas 

 of the archesporium, tapetum, and the development of the spore 

 can be mastered in the case of the fern with comparative ease. 



As for the prothallus, it is admitted to be the most accessible 

 of all, and advantages may be claimed for its independence as a 

 chlorophyll -bearing structure, in spite of its flatttened and some- 

 what specialized form. The antheridia are curious, no doubt, 

 but the spermatocytes and antherozoids and their development 

 are easily made out so far as general features are concerned : the 

 archegonia are not so typical, perhaps, as those of the moss, 

 but they are sufficiently so to be very useful, and the oosphere, 

 canal-cells, &c., are easily seen by an apt student. 



Moreover, I would point out that in the hands of a properly 

 guided student of average intelligence, the teacher can rely upon 

 the fern prothallus for introducing some theoretical notions very 

 difficult to acquire — e.g. the gradual separation of the sexual 

 organs, and their withdrawal into the prothallus, and the 

 eventual separation of male and female prothallia, and their 

 reduction and withdrawal into the spores, leading to the final 

 specialization of male and female spores, and their retention 

 and reduced germination inside the sporophylls, which also 

 become specialized. 



I should explain here that I would not propose to carry this 

 explanation of homologies too far at this stage, but my argument 

 is that the foundations for much that is to follow can be laid now 

 with better effect than at any other time. It may be contended 

 that the elementary student cannot possibly understand the 

 Hoffmeisterian morphology until he has mastered the structure 

 of the ovule of the Phanerogam, and that, therefore, it makes 

 no difference in this respect whether he begins at the one end or 

 at the other. I grant this, but my plea is not for the crowning 

 of the student's knowledge of morphology, but for the founda- 

 tion of it, and I lay so much stress on his laying this foundation 

 thoroughly — otherwise it will not bear the weight of the super- 

 structure I should propose to raise on it — that I look for the best 

 type for that purpose ; and, bearing in mind that such a type 

 must be convenient, and one wherein the student can find the 

 objects and examine them himself, I believe it has been found 

 in the fern. 



It will no doubt be remarked that, in the preceding discussion, 

 I have kept in view more especially the study of morphology as 

 the aim of the young academical botanist, and that it is because 

 the fern is so excellently situated midway in the vegetable 

 kingdom that it forms so good a type for teaching purposes. 

 If it is urged, however, that physiology is the study to be more 

 especially kept in view, then it may be necessary to reconsider 

 the question of a type. 



But there are two reasons, to my thinking, for discarding the 

 idea that the study of physiology should be the immediate aim 

 of botanical teaching in schools at present, though I do not 

 despair of its introduction in the near future. 



Firstly, the appliances needed, simple as they are in most cases, 

 nevertheless are appliances, and will, as matter of fact, bar the 

 way to the study during school life for some time to come ; 

 secondly, however much we may insist that the study of the 



NO. TO95, ^<^L. 42] 



physiology of plants presents its own problems and phenomena 

 apart from those proper to physics and chemistry — and no one 

 can urge this more earnestly than I do myself^nevertheless it 

 cannot be gainsaid that the student of physiology should have a 

 fair acquaintance with elementary physics and chemistry, even at 

 the outset. I am aware that the contrary has been asserted, and 

 that it has been argued that a student may learn to rig up 

 apparatus for demonstrating the respiration of germinating seed!s 

 without knowing anything about the properties of oxygen, or 

 what happens when carbon dioxide passes into a solution of 

 barium hydrate, and that he may perform experiments on assimi- 

 lation knowing no more about starch than that it turns blue 

 with iodine, or on transpiration without understanding anything 

 of the physics of the atmosphere or of water ; and I am not 

 prepared to say that such training would be without benefit, but 

 apart from the advantages of the preliminary knowledge of 

 phenomena, every teacher knows how dull is the comprehension 

 of the boy's mind when brought face to face with such experi- 

 ments devoid of the necessary physical concepts, as they have been 

 termed ; and in any case the necessary minimum of physics and 

 chemistry will have to be instilled at the time the experiment is 

 performed. 



Secondly, the study of histology — practical acquaintance with 

 the microscope — is a necessary preliminary to physiology, and I 

 am d'ubtful whether we are at present in a position to demand 

 more than the beginnings of these matters from the schools, 

 though the time will come when it will be disgraceful for a boy 

 to leave school quite ignorant of them. 



The study of the fern should be followed by that of the 

 -fitie, and I am not prepared to demand a continued adherence 

 to the type-system beyond this point, except under special and 

 favourable circumstances, such as need not here be discussed. 

 Indeed, I should be quite satisfied if we could depend on school- 

 children learning how to describe plants fairly accurately, and on 

 the boys and girls in secondary schools knowing something more of 

 field botany and how to use a flora, and having a satisfactory 

 acquaintance with the life-history and structure of a fern and a 

 pine. When I speak of field botany as above, it is not intended 

 to exclude an acquaintance with the external appearance of com- 

 mon Algse, Fungi, lichens, and mosses, &c., though the extent of 

 that acquaintance would necessarily depend upon circumstances. 



It must not be overlooked, however, that somewhere between 

 this stage and that of further progress to the higher departments 

 of academic botany, the student will have to do some compara- 

 tive anatomy and histology, on the one hand, and to master the 

 details of the life-history of certain types of Algse, Fungi, and 

 Lichens, Muscinese and Vascular Cryptogams, and look more 

 deeply into that of the Phanerogams. 



It depends on circumstances whether the type-system should 

 be followed here or not. If the student is going to specialize in 

 the direction of morphological botany, I am inclined to the 

 opinion that he should steadily pursue the type-system, supple- 

 menting his work with comparing special structures selected 

 from allied types as he proceeds. For instance, after working 

 through the life-history of a Pythitim, he should not need to 

 devote his attention to actually exploring all the details in the 

 life history of Mticor and Peronospo7'a, but he should see the 

 sporangia of these, and the haustoria of P. parasitica; and 

 again, having worked through the chief stages in the life-history 

 of Marchantia and Funaria, say, there is no need to insist on 

 the same pursuit of detail in the case of other Muscineas, but the 

 student might compare with the corresponding structures in his 

 types the sporangia of Anthroceros and J ungermannia. &c., 

 the leaves of Sphagnum and Polytrichimi, and so on. 



If the student is more inclined to the pursuit of physiology, I 

 should prescribe a different course as soon as he has examined a 

 few tyi es of Algse and Fungi, a moss, and a few Vascular 

 Cryptogams, and I should, moreover, direct his attention at 

 once to the highest plants — the Angiosperms — instead of leading 

 up to them as in the case of morphological studies. 



In fact, the system to be pursued for a training in physiology, 

 is to select the best illustrations of the organs, the tissues, and 

 the histological elements of which the functions are to be 

 studied. For the typical root I should go to one plant, but it 

 might be necessary to employ quite another plant for showing 

 root-hairs or root-cap : while selecting the vascular bundles of 

 Ranuncuhis repens or of Aristolochia to show certain facts about 

 the bundles as a whole, I might take those of Cucurbita for 

 sieve-tubes, those of Linum or Vinca for bast-fibres, and those 

 of quite other plants for spiral or pitted vessels, &c. 



