3i8 



SCIENCE. 



[Vol. XXII. No. 566 



liundred and twenty hours or thereabouts that form the 

 available allowance in a single term, even after the attain- 

 ment of a fair knowledge of phsenogamic botany. To 

 acquire the necessary skill in the use of the compound 

 microscope will alone consume no small part of the time, 

 and without this nothing of value can be done among the 

 cryptogams. 



Again, to tell a class the name of a plant instead of 

 teaching them how to discover it for themselves is to rob 

 the study of much of its special value in training the fac- 

 ulties of observation. This part of the work compels a 

 close and repeated examination of the plant and renders 

 the parts and their names thoroughly familiar as no other 

 method can do it. And speaking from a long experience, 

 I cannot believe that the art can be acquired by less 

 practice than that afforded by the analysis of the fifty or 

 more specimens usually required, unless, as is sometimes, 

 and as should be always done, the description of the 

 plants is made a part of the work. And this description 

 should consist not merely of the filling up of the forms 

 usually suf)plied, whereby the exercise is robbed of much 

 of its value, but by requiring the whole from the scholar, 

 thereby training him in recollecting what to look for 

 without suggestions or leading questions. No practice in 

 elementary botany is so useful as this. 



Of course a part of every class, especially if it is large, 

 will shirk the labor when they are out of the class-room. 

 But shirking in the way suggested can easily be j)re- 

 vented by giving a plant which has no English name and 

 in general by testing a scholar's progress by the work 

 done in the class-room from day to day. 



I need not do more than allude to the difficulty, I may 

 say the impossibility, of supplying elementary classes 

 with microscopes of sufiicient power for the purpose ad- 

 vocated in the paper here referred to, without which the 

 study must degenerate into a mere absorption of what 

 the teacher tells. This would be little more than a waste 

 of time and a degradation of science to the level of a mere 

 memory study. 



On yet one other point I must disagree with this au- 

 thor. There was, some years ago, a disposition to begin 

 the study of a science at the bottom and work upward, and 

 this in spite of strong remonstrances from many teachers 

 of great ability and experience. Even a man like Hux- 

 ley fell into this error, as may be seen in the early edi- 

 tions of his " Biology." But a few years' test showed the 

 many disadvantages of this method, and the opposite, or 

 older plan has been readopted. Whatever may be urged 

 from the standpoint of theory, practice is unanimous on 

 the other side. Steady advance from the known to the 

 unknown is easier than a plunge into the mysteries of 

 cryptogamic botany with its abstruse terminology and its 

 minute, often almost invisible structure. For every one 

 who might be attracted by the delicacy and difficulty of 

 the subject a thousand would be disgusted and disheart- 

 ened and would forsake the study forever. 



The author's illustration from geology is unfortunate 

 because in teaching this subject the best plan is to begin 

 neither with the superficial nor the deep rocks. This 

 savors of book geology. The proj^er plan is to begin 

 with whatever rocks happen to lie within the range of the 

 student's investigation. Here again we work from the 

 known to the unknown. 



The object of the teacher in every study should be to 

 stimulate to farther advance, and this cannot, I think, be 

 accomplished excejjt by beginning with the easy and the 

 obvious, and by assigning tasks well within the sti'ength 

 of the student. If a fair acquaintance with the structure 

 of the phsenogams and the methods of phsenogamic bot- 

 any can be attained in the first term devoted to the study, 

 the time will have been well spent, and neither the 



teacher nor the average scholar can reasonably expect 

 much more. E. W. Cl.^\pole. 



Akron, Ohio. 



Coral Reef Formation. 



In Science for Oct. 20, p. 214, I observe that Professor 

 Perkins gives a succinct account of the history of the 

 theories of coral reef formation. Darwin and Dana have, 

 of course, their proper place in connection with the "sub- 

 sidence theory." Agassiz is justly mentioned as declaring 

 that there was no subsidence in the case of the Florida 

 reefs. Guppy and Semper are very properly mentioned 

 along with Murray in connection with the new views; but 

 my name is not mentioned in that connection. Let me, 

 then, quote from a paj)er of mine read before the A. A. 

 A. S., Aug., 1856, and published in the Proceedings and 

 also in the Am Jour., Jan , 1857: "On sloping shores 

 with mud bottom, such as we have supposed always ex- 

 isted at the point of Florida, a fringing reef cannot pos- 

 sibly be formed, for the water is rendered turbid by the 

 chafing of waves on the mud bottom; but at some dis- 

 tance (in this case ten to twenty miles), where the depth 

 of sixty to seventy feet is attained, and where the bottom 

 is unaffected by waves, the conditions favorable for coral 

 growth would be found. Here, therefore, would be 

 formed a barrier reef, limited on one side by the muddi- 

 ness and on the other by the depth of the water." 



This is positively the first attempt to explain barrier reefs 

 without resorting to subsidence. Captain Guppy worked 

 out the same explanation independently long afterward, 

 but on becoming acquainted with my paper promptly ac- 

 knowledged the anticipation of his views. I quote from 

 a communication by him to Nature (Vol. 35, p. 77, 1886): 

 "When I arrived at the above conclusions I was not aware 

 that substantially the same explanation had been ad- 

 vanced thirty years before by Prof. Joseph Le Conte in 

 the instance of the reefs of Florida. * * * * ihe 

 circumstance that barrier reefs are frequently situated at 

 or near the border of submarine plateaus receives a ready 

 explanation in the view first advanced by Professor Le 

 Conte." 



When I wrote my paper I did not dream of generaliz- 

 ing my conclusions or of invalidating Darwin's theory ex- 

 cept as applied to Florida. The subsidence theory was 

 to me then, as it is now, the most probable general the- 

 ory for the Pacific reefs. I am little disposed to make 

 reclamations. Except on the score of history, it matters 

 little who first brings forward an idea. My paper is now 

 thirty-seven years old. In the midst of all these discus- 

 sions of new views I have been silent. My paper, there- 

 fore, has almost dropped out of the memory of the 

 younger generation of naturalists. This is my only ex- 

 cuse for bringing it up now. Joseph Le Conte. 



Berkeley, Cal., Nov, lo. 



BOOK-EEVIEWS. 



Tables for the Determination of the BocJcforming Minerals. 

 By F. Loewinson-Lessing. Translated by J. W. Greg- 

 ory. New York and London, Macmillan k Co. 55p., 

 8vo., Sl-25. 



The literature of micropetrology has of late received an 

 interesting addition in the shape of a translation by J. W. 

 Gregory of F. Loewinson-Lessing's tables for the deter- 

 mination of rock-forming minerals. Unlike the Hi'dfsta- 

 bellen zur Mikroskopischen Mineralbesiimmung of Eosen- 

 busch, or the Tableaux des Mineravx des Roches of Michel, 

 Levy and Lacroix, the work is something more than a 

 bare list of the rock-forming minerals with their optica] 

 proj)erties, but has for its avowed purpose an attempt to 

 ajDply to micropetrology the syste'Tl "so long applied in 



