522 SUMMARY OF CURRENT RESEARCHES RELATING TO 



is not a difficult thing to master. And this, indeed, has been the case 

 in our experience with students who have come to us for instruction in 

 histology. The first rude awakening often comes to the beginner when 

 he takes his text-book cut as a guide to lead him through the intricacy 

 of his first mount. Everything looks so differently from what he ex- 

 pected, and even the instructor, in attempting to point out the features 

 so clearly displayed in the cut, will for some time meet with but feeble 

 success. It may be urged that the difficulty is that the eye requires a 

 special training to enable it to convey a correct impression under 

 conditions to which it is not at all accustomed. This is very true ; but 

 is it the only reason for such complete (and not uncommon) failures to 

 see anything at all ? It seems to us that one cause of failure is to be 

 looked for in the illustrations, and the reason is, generally, that they 

 are too diagrammatic. We think that the better class of illustrations 

 in question are very helpful to the advanced worker, not because they 

 are true pictures — for they are not — but that he has learned to take 

 something for granted, and to make just the proper allowances to enable 

 him oftentimes to know exactly what the artist intended. No specimen, 

 however well prepared, can show such clear differentiation of its com- 

 ponent parts as the illustration which represents it. The latter has 

 caught the general features, exaggerated them, and bothered not at all 

 with the spirit of its subject. The aim, moreover, has been apparently 

 to picture the specimen not as it looks, but as it is. For the benefit of 

 the beginner this should be reversed ; he must first learn to see the 

 specimen as it looks, and then be taught to know it as it is. 



The difficulties at the root of the matter seem to be (1) the fact that 

 the delineations are not confined to that which is seen at a single focus, 

 but are deduced from a knowledge gained by a study of several focuses, 

 and (2) the process employed. 



(1) It is this which makes complete tubules in a section where there 

 are few, if any, and which fills up the indistinct spaces with ideal 

 representations of that which, though not seen, is known to be there. 



(2) The process usually employed makes use of distinct lines, some- 

 thing seldom seen in a specimen. A skilful artist could probably etch 

 a tolerably correct picture, and he would do so by carefully toning down 

 his lines to the proper degree. 



Photography and many new processes are coming into use, some of 

 which, it is hoped, will prove more satisfactory. And yet we think that 

 much better work could be done with the method now in vogue (drawing 

 with the use of a camera lucida and photo-engraving the result) if the 

 artist confined himself to drawing that only which he sees at one focus, 

 and conserving that blending of parts which, though sometimes amounting 

 to indistinctness, has at least the merit of being natural." 



Leeuwenhoek's Discovery of Micro-organisms.* — Herr J. F. Schill 

 points out that 1674 and not 1675 should be taken as the date of 

 Leeuwenhoek's discovery of organisms. Attention is directed to a letter 

 dated Sept. 7th, 1674, which appears in the 'Philosophical Transactions' 

 of Nov. 23rd, 1674, and which seems to confirm his contention. 



Collected Papers of T, It. Lewis.f — The 'In Memoriam' volume 

 which contains the collected papers of the late Dr. T. R. Lewis should be 



* Zool. Anzeig., x. (1887) pp. 685-6. 



t Published by the Lewis Memorial Coininiltee. Ito, London, 1888, 732 pp., 

 43 pis., and numerous woodcuts. 



