274 



NATURE 



[January i8, 1900 



Fig. II. is the same view, taken immediately after I., but 

 with the poJariser opened a little. 



Fig. III. was taken after the slide had been treated with 

 Canada balsam and benzene, and allowed to stand five days 

 ifixed in the microscope. The benzene and Canada balsam 

 gradually diluted the solvent and brought back the anisotropism 

 of the nitro-cellulose fibres. 



The magnification in all photos was x 50 diameter, and the 

 exposure in I. and III. was in each case twice that of II. 



In Fig. I. it will be observed that a little light is active 

 besides the crossed cotton fibres. This is more noticeable in 

 the negative. As a matter of fact, with this strength of acetone 

 the anisotropism is just evanescent in a percentage of the fibres. 



A comparison of Figs. II. and III. shows that nearly all the 

 iibres seen in II. are anisotropic in III. The fibres obvious in 



II. and not evident in III. lie in the plane of polarisation. The 

 fibres obvious in II. and III. are isotropic in I. 



I leave the correct interpretation of these experiments to 

 competent biologists. To me it seems probable that the aniso- 

 tropism of fibrous cellulose is due to a strain put on the fibre by 

 the tension of the most outward layer of the cell -wall, and that 

 a medium such as here described lessens this tension, whereas 

 ordinary inhibition does not. Some such a theory as the above 

 seems necessary to account for the different action of solvents 

 which swell organised structures. This view is a modification 

 of Strasburger's theory, as I understand it, and would be inde- 

 pendent of whether cell growth takes place by lamellae or 

 particles. F. W. Jones. 



Barwick, Herts. 



School Science and Knowledge-Making Power. 



The lecture of Prof. J. G. Macgregor, as reported in 

 Nature, of December 14, is of very great interest to science 

 teachers, more especially to those in secondary schools. It 

 will afford great comfort to the still very large number of con- 

 trollers of the curricula in such schools who do not really sym- 

 pathise with, nor believe in, the good results obtained from 

 scientific teaching. As one who has to deal with all ages of 

 pupils in a large school, may I be allowed to make a few com- 

 ments on Prof. Macgregor's lecture as it strikes a science 

 teacher ? 



In class work it seems that the lower forms, when watching 

 an experiment performed before them, are quicker to put one 

 thing with another, and to be led to explain or suggest explana- 

 tions of the results obtained. This is apparently in accordance 

 with Prof. Macgregor's opinion, that younger pupils have a 

 greater knowledge-making power. 



Thus a class of boys, whose ages range from seven to nine 

 years, is much more ready to ask and answer questions con- 

 cerning the subject of the lesson than classes towards the middle 

 of the school. 



The reluctance shown, or the difficulty felt, by higher classes 

 in answering or suggesting questions is considered by Prof. 



NO. 1577, VOL. 61 j 



Macgregor to show a lessened power of knowledge-making 

 possessed by them. But even if the science teaching is, 

 throughout the forms, of a constant character in its aim of bring- 

 ing out the inquiring spirit, in my own experience the same 

 thing is noticed. Can there be another explanation ? As boys 

 grow older they are more careful not to make such mistakes in 

 their verbal answers as would lead to the slightest ridicule on 

 the part of their class fellows. Thus, by remaining silent, they 

 give one the impression that they are not following the work with 

 the ability shown by their juniors. Again, with increased ex- 

 perience, questions do not appear so simple in their nature ; 

 alternative explanations are suggested to the boy's mind, and 

 the choice is difficult to make. It is possible that the few sug- 

 gestive solutions offered by a higher form show more power 

 than the many more obvious ones given by the lower form. 



Prof. Macgregor says that at present Latin is the only subject 

 which really brings out this knowledge-making power. Surely 

 this is comparing the results obtained from the best classical 

 teaching in small selected forms where each boy is really known 

 to have done his work to the very best of his ability, with the 

 results from science teaching of a very old-fashioned kind, in 

 which the lesson, given to a large class, is of the nature of a 

 lecture. Such a comparison may be made to the disadvantage of 

 any educational subject. It is still the custom in some classes 

 to learn Euclid's propositions by heart ! Yet no one would 

 think of displacing the subject on this account. 



Referring to the difficulties of increasing the knowledge- 

 making povyers of boys, certain enemies are mentioned. There 

 is the use of synoptic or cram-books, which has been found to 

 be necessary to push pupils through examinations in which 

 " knowledge is power " is held as the maxim. Such books, 

 after all, only take the place of written notes of lectures given 

 to the highest forms, and have the advantage of saving the 

 pupil's time. Further, text-books do not all consist of this 

 kind of publication ; in fact, some of them are as interesting 

 to an intelligent boy as one of the ordinary run of story-books. 

 Properly used, text-books are of great value surely in this way : 

 the whole attention of the scholar is directed to the demonstra- 

 tion, and after the lesson the book is used to refresh the 

 memory, which it does, not simply by repeating the results, but 

 also the deductions from the results and the necessary steps of 

 reasoning involved. 



Prof. Macgregor objects to text-books which contain details 

 of practical work to such an extent that the pupil is told what 

 to do, what to expect, and the reasons why. If the teaching is 

 carried out under such a system as that referred to as the 

 Heuristic, then in the practical text-book it is not neces- 

 sary to include all these details, but some appear to me to 

 be absolutely necessary. Teachers know well enough the 

 difficulty of getting printed instructions accurately carried out ; 

 and certainly letting even a small class of moderately steady 

 boys loose into a laboratory would give the controller of the 

 laboratory an anxious time. If, then, instructions are needed, 

 why not print them ? They must otherwise be written on the 

 blackboard, or be of a verbal nature— the latter involving many 

 repetitions. 



The best chance that practical science (of course, commenced 

 as early as possible) has of producing knowledge-making power, 

 appears to be in the opportunity it affords of solving questions 

 in a manner closely following an experiment previously carried 

 out. In this connection modern science teaching combines the 

 advantages of the study of propositions in geometry and riders 

 thereon, with employment, simultaneously, of brains and hands. 

 Now an experiment previously carried out implies instructions 

 given. 



The other enemy referred to by Prof. Macgregor is the ex- 

 amination syllabus. It is certainly difficult under the best of 

 circumstances for a teacher to go completely through, say, the 

 Cambridge local examination syllabus in science on the Heuristic 

 system, in the time usually allowed by school time-tables. With 

 such a task in front of him the teacher is bound at times to 

 descend, so to speak, to dogmatic teaching. The modern syl- 

 labus, both in this examination and in that for the London 

 matriculation, covers so wide a ground that there is danger of 

 the work becoming of the same character as it is said to have 

 been under the older syllabuses. It would appear, even now, 

 to be absolutely necessary to use " synoptic books" \yhen such 

 lengthy syllabuses are prescribed and written examinations held. 



But it is hard to see how even a practical examination can 

 test the knowledge-making power of boys when a lapse of 



