970 SUMMARY OF CUERENT RESEARCHES RELATING TO 



understood ; structureless membranes and tissues are fast losing their 

 place in histology, and once simple protoplasm is now most complex. 

 What I infer is that the stripes do not mark the positions of alter- 

 nating layers of different structure, the presence of which are 

 ordinarily maintained." 



[We do not, of course, intend to express any opinion as to the 

 real nature of muscular striation, our object being to recall the fact 

 that the appearances presented by muscular fibre are not phenomena 

 of geometrical optics and cannot be explained, nor the problems to 

 which they give rise settled, on " simple laws of geometrical optics," 

 a fact which is readily tested by experiments which it is in the power 

 of any one to make. 



If a piece of muscular fibre, which shows the striation well, is 

 observed with a narrow incident pencil of direct or oblique light, and 

 the eye-piece removed, a row of diffraction spectra will be seen at the 

 back of the objective. If all these are shut off by a suitable 

 diaphragm as in the well-known experiment, all striation disappears, 

 or if some only are admitted — in varying combinations — a great 

 variety of entirely different appearances will be obtained from the 

 same fibre. 



Whether, therefore, the phenomena of striation are due to the 

 internal structure of the fibre or not, they are not phenomena of 

 geometrical optics, which can of course tell us nothing as to optical 

 images which depend on the admission or non-admission of diffracted 

 light.] 



Microscopy in 1830-1881. — Amongst the multiplicity of subjects 

 to be dealt with, microscopy could be accorded but a brief reference 

 in the Presidential Address at the York Jubilee Meeting of the British 

 Association, confined to the question of the visibility of atoms. Sir 

 John Lubbock stating that " we cannot, it would seem at present, 

 hope for any increase of our knowledge of atoms by any imj^rove- 

 ment in the Microscope. . . . Even .... if we could construct 

 Microscopes far more powerful than any we now possess, they would 

 not enable us to obtain by direct vision any idea of the ultimate 

 molecules of matter ; . . • there may be an almost infinite number 

 of structural characters in organic tissues which we can at present 

 foresee no mode of examining." 



It will not now be many years before this Society will have to 

 celebrate its Jubilee, when the progress made in the mechanical, and 

 still more in the optical arrangements of the Microscope, during the 

 fifty years of the Society's existence, will no doubt be enlarged upon 

 either in the Presidential Address or otherwise. 



Obituary. M. Nachet, Sen., and Mr. C. A. Spencer. — We have 

 to record the death of M. C S. Nachet, Sen., the founder of the 

 eminent firm of French opticians, which took place at his residence 

 in Paris on the 28th ultimo, in his eighty-third year. He was one 

 of the earliest in France to devote himself to the construction of 

 achromatic objectives for the Microscope. In 1834 he entered the 

 house of Chevalier, and during six years his exertions contributed 



