1881.] 



MICROSCOPICAL JOURNAL. 



227 



of sufficient power to distinctly show 

 the worms. The lens can be readily 

 focussed by the screw-fitting. 



The new turn-table, represented in 

 Fig. 54, is an ingenious affair, and 

 runs very smoothly. It is provided 

 with a hand-rest, shown in the cut, 

 which can be readily adjusted to any 

 convenient height. 



Motion of Diatoms. 



I am able to confirm, from actual 

 observation, the correctness of the 

 views of Dr. Wallich, as quoted by 

 your correspondent "J. D. C." (Mi- 

 croscopical Journal, Nov., i88i, 

 p. 2o6), relating to the Motions of the 

 Diatomace?e. 



Mr. Wallich ascribes these motions 

 to " the existence of prehensile fila- 

 ments, capable of alternate extension 

 and retraction, of extreme tenuity, 

 yet of extraordinary strength and 

 elasticity." 



I have not been able to see these 

 filaments in living diatoms, and there- 

 fore I cannot verify the assertion as 

 to their " alternate extension and re- 

 traction," but as these filaments are 

 undoubtedly composed of protoplasm 

 and may be fairly compared with the 

 pseudopodia of the Rhizopods, there 

 is no reason to doubt that they pos- 

 sess this power. 



I have seen them frequently, in cer- 

 tain diatoms found in abundance in 

 'the gutters of New Orleans. (A pho- 

 tomicrograph of one of these is en- 

 closed herewith.) 



My observations were made during 

 the summer of i88o, while especially 

 engaged in studying the bacteria 

 found in the same situation in great 

 variety, and the demonstration was 

 made with the ^-inch homogeneous 

 oil-immersion objective of Zeiss, and 

 by the use of iodine solution as a stain- 

 ing fluid. The vitality of infusoria and 

 of diatoms is instantly arrested by a 

 2-5 p. c. solution of iodine, dissolved 

 by means of potassium iodide, and 

 the slender filaments referred to are 

 brought into view by the staining of 



the/ protoplasm, and by a prompt 

 coagulation which prevents them 

 from being withdrawn, as would very 

 likely occur if their vitality was not 

 instantly arrested. The cilia of cili- 

 ated infusoria, such as Paramecium, 

 etc., are beautifully shown by this 

 method, with comparatively low pow- 

 ers. They project from the body like 

 rigid rays and may be photographed. 

 I have not yet made the attempt to 

 show the filaments referred to, de- 

 pending from the lower valve of a 

 diatom suddenly killed by iodine so- 

 lution, but believe that this would be 

 quite practicable, although a more dif- 

 ficult matter than the photographing 

 of the cilia of infusoria, and perhaps 

 as difficult as the demonstration of 

 the flagella of B. termo, which, I con- 

 fess, I have not succeeded in making. 

 G. M. Sternberg, 



Surg. U. S. A. 

 Fort Point, San Jose, San Francis- 

 co, Cal., Dec. 2d, 1881. 



New Metliod of Mounting But- 

 terfly-scales.* 



Dissolve one part of AnT:hony's 

 " French diamond varnish " in two 

 parts of pure benzole. Apply a drop 

 or two of the solution to a slide, and 

 in a few seconds, or as soon as the 

 varnish has set, press the wing of the 

 butterfly gently upon the slide, and 

 then carefully lift it away. The scales 

 will be found transferred to the slide 

 in their beautiful natural arrange- 

 ment on the wing. Make a shallow 

 cell around the mounting and apply 

 the cover-glass. Canada balsam must 

 not be used, as it disarranges the 

 object. 



o 



The Preparation and Mounting 

 of Salicin Crystals.* 



The following apparatus is recom- 

 mended : — 



I St. A kerosene lamp, or an ar- 

 gand gas-burner, with a long chimney. 



* Read before the New York Microscopical 

 Society, by Mr. B. Braman. 



