1888.] MICROSCOPICAL JOURNAL. 113 



EDITORIAL. 



Photomicrographs. — We have received a set of several photomicrographs 

 from Mr. Geo. W. Rafter, from whose letter we quote as follows : — ' The pleuro- 

 sigmas may serve to illustrate my paper on " Use of Amplifier." The pleu- 

 rosigmas of 400 diameters are with l" objective of B. & L., student series, and 

 illustrate in the strongest manner the value of the amplifier. The other pleu- 

 rosigmas are with B. & L. y first-class, and I think I may say thev compare 

 with any yet inade. The plant sections are with B. & L. 2" professional, 

 without amplifier.' The photographs are very fine, indeed. The P. angii- 

 latuin^ with power of only 400 diameters, if examined with hand lens, even 

 bears comparison with the picture of /*. angulatum magnified 900 diameters 

 with amplifier. The latter is as good as any w^hich we have ever seen. The 

 'beading' is shown as clearlv as it could be seen with a microscope. The 

 plant sections are admirable. In one of them — the cross-sections of the stem 

 of sumach — the gross structure is shown as clearly as it could be shown by 

 the most faithful and careful di'aughtsman. It looks almost as if photographed 

 from some of the wonderful figures in Sach's text-book. We. shall be glad to 

 send these photographs to any who care to examine them and will return 

 them free of cost to us. 



He has also sent a second large series of 3 2 prints from plant sections and 

 18 diatoms which show admirable work. In most of the prints the features 

 of the original are reproduced with almost as perfect clearness as in the orig- 

 inal view. The P. angulatu7}i magnified 900 diameters is a marvel of clear, 

 crisp definition, thoroughlv well ilkuninated, as is also Cynibella gastroides 

 magnified 1000 diameters. The plant sections from Phsenogam stems are all 

 of them excellent, and could be passed about at a society to illustrate any point 

 in the structure which it might be desired to demonstrate. 



And this brings us to a second thought in connection with the gift of Mr. 

 Rafter, which is the place which photomicrography plays in the studies of a 

 biologist. It has always been our opinion that a perfect representation on 

 paper from a prepared slide could not be made by photography. We em- 

 phasize the word perfect, for we think that next to the drawing by an actual 

 artist who can put together the result of several looks at various focal levres 

 the picture of the camera is perfection. Every one who understands what a 

 boon the camera lucida is can see the value of the photographic camera. The 

 greatest benefit, however, from the photomicrograph is the result — a picture 

 which can be passed around at the club meeting or in the lecture room to 

 illustrate a slide. It does away with the cumbrous and inconvenient magic- 

 lantern, and enables one to illustrate most conveniently. For lecture room 

 or club meeting the photographs are most useful. Mr. Rafter has also offered 

 an important suggestion that in staining sections attention be had to the 

 value of the mount for photographic purposes. 



— — -o 



Physiological reversion and the Darwinian theory. — Dr. T. W. 

 Mills, of McGill College, Montreal, has, in a recent article,* attempted to 

 show the meaning of certain facts, some of which were of his personal observa- 

 tion and others which are well known. His paper, as he says, is not the first, 

 Dr. Fothergill, of London, having, in 18S6, unbeknown to the author, enun- 

 ciated the same principle. After speaking of the well-known embryological 

 fact that the highest mammals pass through stages of development closely 

 allied to permanent forms of groups of animals lower in the scale, the author 

 proceeds to show that the organs of the higher animals strongest in coping 

 with disease are those which have been acquired, and which are not pos- 



* Science, vol. xi, p. 79. 



