ROOD^ ON APPLICATION OF PHOTOGRAPHY TO MICROSCOPE. 261 



gelatinous matrix was apparent, and I cannot say wliat may 

 have held them together. Of the meaning of this very remark- 

 able condition I cannot form any idea, except to guess the 

 possibility of its being an approach for the purpose of con- 

 jugation, on a scale, indeed, wholesale. No alteration took 

 place, cither in their internal or external appearance, though 

 kept for some time ; and I then unfortunately lost the speci- 

 mens. One thing, however, seems to me certain — the hanging- 

 together of the fronds in the manner shown did not indicate 

 longitudinal self-fission after the mode in Ankistrodesmus, 

 for in the same gathering dividing fronds occurred after the 

 manner normal and generic in this and other species of Clo- 

 sterium (figs. 61, 62, x 200), and the combined fronds were 

 all mature and fully grown, and were quite specifically 

 characteristic. 



On the Practical Application of Photography to the 

 Microscope. By Professor O. N. Eood, Troy, N.Y. 



While the value of the photographic delineation of micro- 

 scopic objects, as a means of accurately recording observa- 

 tions, seems to be generally acknowledged, yet, owing to the 

 real or imaginary difficulties with which the process is beset, 

 but very few working microscopists have adopted it."^ After 

 eight months of steady experimental work on the subject, this 

 fact appears to me a matter of astonishment, for the difficul- 

 ties, which are not inherent, mostly disappear when proper 

 precautions are taken. I propose to mention briefly certain 

 points in my experience, and to indicate the methods pursued. 



Arrangement of the apparatus. — The microscope is brought 

 into a horizontal position, and connected with a camera box 



* In Vienna microscopic photographs have been produced under the 

 direction of Auer. Pohl and Weselsky have also worked at this subject. 

 (' Sitzungsbericht d. Kais. Akad., 1857, xxiii, vol. 1, page 317) ; at an earlier 

 date Mayer, of Frankfort, obtained flue photographs of this kind. Bcrtsch 

 presentedsimilarresultstotherrenchAcademy('ComptesE.eDdus,' 1857,xliv.) 

 Nacliet also obtained good results. Hodgson (' Quart. Journ. of Micros. 

 Science' 1853, ii, p. 117), Delves (3d No. of the same, p. 57), Shadbolt 

 (ibid., p. 165), Huxley (ibid., p. 178, also No. 4, p. 305), Wenham (same 

 journal, 1855, No. 10, p. 1), and Kingsley 'Phil. Mag.,' (1853, June, p. 4G1), 

 have published accounts of their more or less successful results. Harting 

 'On the Microscope,' Braunschweig^ 1859. To the above must be added the 

 great work now beiug issued in numbers in ^Munich, entitled 'Atlas der 

 allgeminen theirischen Gewebelehre, herausgegeben von Th. v. Hessliug uud 

 J. Kohmann, nach der Natur photographist von Jos. Albert.' 



