1888.] MICROSCOPICAL JOURNAL. 103 



Drawings y. Photographs. 



By Dr. GEORGE A. PIERSOL. 



At the present time when, to ahnost every microscope, a photographic cam- 

 era is being attached, and when photomicrographs, of every degree of merit, 

 are being produced on all sides, it maybe well to weigh the respective values 

 of the pencil and sunbeam as meaii^ of recording the observations of the in- 

 vestigator. The idea of reproducing, by photography, what is seen in the 

 microscope, is so captivating that it is a matter for little surprise that so many 

 undertake the work. These remarks do not apply to the photographing of 

 preparations for the purpose of producing excellent pictures, but bear upon 

 the merits of the two methods as auxiliaries to the work-table. That the pencil 

 is being unwisely neglected, owing to a too implicit reliance on photography, 

 is an unfortunate present tendency — especially for the young investigator, 

 who loses the training to accurate observation which the conscientious use of 

 the pencil brings. But both the photographic camera and the drawing-prism 

 have their advantages, and the investigator can afford to dispense with neither, 

 as, by their judicious employment — sometimes by their combination — more 

 satisfactory and valuable results are obtained than are possible by any exclusive 

 adherence to either. 



An experience in photomicrography, which warrants a full appreciation of 

 its value and capability, has taught that the most serviceable and satisfactory 

 field of photography lies at the extremes of the table of amplification — with 

 very low (20 to 70 diam.), and with very high powers (500 to 1500 diam.) 

 What drawing can equal, in beauty of detail, a really good photograph of a 

 suitable specimen taken with a fine low power objective ; who can draw 

 fibrillae of striated muscle, a group of bacteria, or a delicately marked diatom 

 in competition with photographs.' Excellent pictures are made under ordi- 

 nary magnifications (200 to 350 diam.), but in the majority of cases there is 

 much less cause for congratulation. Leader these circumstances, the con- 

 scientiously and skilfulh' used pencil will produce a more valuable and sat- 

 isfactory record for the investigator than the camera. The reason that good 

 photographs, with very low or very high powers, are so satisfactory is, that 

 under both conditions suitable lenses reproduce all the planes of tissue neces- 

 sary for a serviceable representation of the object; nine times in ten this will 

 not be the case with the pictures demanded of the \ or \. While it is um-ea- 

 sonable to expect the lens to reproduce more than the plane accurately in 

 focus, it is nevertheless true that this physical limitation (reduced to a mini- 

 mum b}' the thinnest possible sections) frequently renders photographs, under 

 medium powers, unsatisfactorv substitutes for more diagrammatic drawings. 



At the present time, the investigator who depends upon photographs tor 

 his illustrations finds himself confronted by the pertinent question as to the 

 manner in which his pictures shall serve as journal illustrations. That pho- 

 tography, in its applications to book-making, is yet in its infancy, no one 

 doubts ; that really beautiful results are already accomplished by the best 

 methods is equally certain : if, therefore, the liberality of the publisher places 

 one of the unexceptional ' processes' at his command, the investigator may 

 feel confident. Let him, however, be cautious as to where he places his hopes 

 when economy is consulted, for there is nothing more annoying to the worker 

 himself, or more unfortunate for the cause of photomicrography, than the dis- 

 semination of those monstrosities whose harsh black and white masses, de- 

 void of half-tone and detail, are supposed to ' reproduce' a really fine neg- 

 ative. 1 



Frequently, however, the use of the photograph is out of the question, and 

 the investigator, or the artist, must make the necessary substitute ; by all 



