1882.] 



MICKOSCOPICAL JOURNAL. 



119 



PHOTO-MICROGRAPHS. 



To THE Editor. — I have been work- 

 ing for some time past to simplify the 

 technique of photomicrography and, I 

 think, with very good success, as I find 

 that by the use of dry-plates I am able 

 to dispense with the use of a heliostat for 

 powers below 600 diameters. 



It will be admitted that this is a great 

 desideratum, as the heliostat is a some- 

 what expensive piece of apparatus, and 

 requires a certain amount of skill for its 

 management. 



It is my intention to give a detailed 

 account of the technique as perfected by 

 myself, in the introduction to a work soon 

 to be published, which will be entitled 

 " Elementary Lessons in Biology," and 

 which will be illustrated by photomicro- 

 graphs reproduced by the heliotype 

 process. 



A communication in the April number 

 of the Microscopical Journal has 

 induced me to send you the photomicro- 

 graphs enclosed with this letter. 



In the communication referred to, Prof. 

 Kain announces his success in making 

 photomicrographs by lamp-light. I made 

 some experiments in this direction in 

 Baltimore last summer, and convinced 

 myself that for low-powers it was quite 

 practicable to use a powerful oil-light, as 

 the source of illumination, but the long 

 exposure required, and the indifferent 

 results I obtained caused me to abondon 

 the oil-light in favor of sunlight reflected 

 from a clear sky. 



I am quite surprised at the brief time 

 of exposure, which Prof. Kain has found 

 sufficient, and would be very glad to see 

 some of his photomicrographs, especially 

 those made without removing the eye- 

 piece. My experiments were made with 

 Carbutt's extra-rapid plates, and without 

 an eye-piece, but the time of exposure re- 

 quired, was so great that I abandoned the 

 method. 



If Prof. Kain, has succeeded in making 

 good photomicrographs, with an oil-light 

 and without removing the eye-piece, in 

 the brief time mentioned, he has certainly 

 done very much to popularize an art 

 which has heretofore presented so many 

 difficulties, and required such elaborate 

 apparatus that considerable time, patience 

 and money were necessarily expended 

 by the few who have been successful in 

 making satisfactory photomicrographs 

 with high powers. 



I have for several months past been 

 working without a heliostat, using light 



reflected from the sky on a bright day. 

 For the highest power mentioned (600 

 diameters), it is essential that the sky be 

 free from clouds, and the atmosphere not 

 at all hazy. I enclose a photomicrograph 

 of bacteria, made in this way without the 

 use of a heliostat. The time of exposure 

 was twenty-five minutes, and the plate 

 was manufactured by the Eastman Dry- 

 plate Co., of Rochester, N. Y. I have 

 been using these plates exclusively for 

 some time past, and am much pleased 

 with them. 



Geo. M. Sternberg. 

 May ist, 1882. 



[We are indebted to Dr. Sternberg, for 

 a number of very excellent prints, which 

 are at this office where they can be seen 

 by any person who is sufficiently interested 

 in the subject to call for them. As re- 

 gards the time of exposure, it is certainly 

 possible to make good negatives with 

 exposures of one and a half to three min- 

 utes, using a student's lamp, as Prof. Kain 

 has stated ; but it is also possible that more 

 detail would be developed by giving an- 

 other half a minute — we have thought so 

 from the result of a recent experiment, 

 but have not made another trial to test 

 the matter. — Ed.] 



MICROSCOPICAL SOCIETIES 



A regxilar meeting of the State Mi- 

 croscopical Society of Illinois was 

 held on Friday evening, April 12th, Dr. 

 Lester Curtis in the chair. 



Dr. Elbert Wing read a paper on " The 

 Arterial Terminations, the Malpighian 

 and Oval Splenic Bodies, and the Honey- 

 comb of Membranes, in the Spleen." 



The writer gave an account of the hon- 

 ey-comb of membranes described and 

 figured by Klein. This honey-comb is 

 only a plexus of blood-vessels, continuous 

 with the arteries on one side and the veins 

 on the other. From the interior of these 

 vessels therfe project buds, which ap- 

 pear to grow and become detached and 

 enter the blood-current. These buds, to- 

 gether with the honey-comb membrane, 

 Klein considers to be the substance of the 

 pulp of the spleen. He then described some 

 investigations on the terminations of the 

 arteries of the spleen, conducted by Drs. 

 H. K. and C. G. Jones, which were sug- 

 gested by some studies on the subject by 

 Dr. Salisbury, of Cleveland, Ohio. Ac- 

 cording to these researches the arteries of 

 the spleen terminated : — 



