104 THE AMERICAN MONTHLY [Jime, 



means let it be the microscopist himself, for he ■will then have the guarantee 

 that the feature of the dra\\ang, especially valuable, is appreciated. Under 

 such circumstances, a combination of the camera and pencil, which the writer 

 has employed since the introduction of the Eastman ' Bromide Paper,' may 

 often be found very satisfactor}^ Selecting the ' B ' grade, and marking out 

 all undesired parts of the negative, a somewhat under-exposed print is made 

 and developed until the cardinal parts of the picture are visible ; this, when 

 dried, yields a black and white sketch which, after being worked over with 

 India ink and hard lead-pencil, presents the appearance of an elaborately fin- 

 ished drawing and, as such, v\^ill be satisfactorily copied by the artist on the 

 block or stone. Where details are very simple, the outlines of the photograph 

 are easily transferred to the drawing-paper by means of the inteiposed sheet of 

 ' graphite ' or ' carboir' paper and the tracing point. 



But, after all, for the busy worker the direct sketch on paper is frequently 

 the most convenient and economical. It is to be regretted that the drawing- 

 prisms in use on the Continent are not more generally used among our own 

 microscopists. An experience embracing all the usual forms has resulted in 

 a settling down to the Abbe apparatus as being the most satisfactory, and, due 

 regard to the inclination of the mirror and the warranted size of the sketch 

 being observed, as leaving little to be desired. After a long observation of 

 struggles with the drawing-prisms usually furnished by American and English 

 makers, it is truly refreshing to see with what ease and accuracy complicated 

 contours are followed with this instrument even at the first attempt. 



With any form of drawing attachment, the nice balance between the illum- 

 ination of the microscopical image and that of the paper is an all important 

 condition ; having had occasion recently to use the Abbe pi'ism to sketch some 

 1400 sections, a simple device of great service was found. This consisted of 

 a light stand supporting a small glass plate (10 < 15 cm.) , two-thirds of which 

 was ' matt,' being ver}^ finelv ground, leaving the remaining third as a clear 

 strip extending in the direction of the greatest length of the plate. The sec- 

 tion being well lighted and focused, and the paper adjusted for the drawing, 

 the screen should be interposed between the source of illumination and the 

 microscope mirror when the object becomes illuininated by a soft diffuse light, 

 very favorable for the rapid and accurate sketching of details. Slight lateral 

 movements of the screen by the left hand soon determine its best position. 

 When a doubt arises as to some detail, a movement of the wrist floods the 

 field with light, enabling an exact observation to be made, while a second 

 change restores the mellow illumination so favorable for drawing. All this 

 can be done without moving the eve from the tube or taking the pencil from 

 the paper. The position of the screen between the light and mirror is more 

 effective than when the ground glass is mounted as part of the substage appa- 

 ratus. Those who have never used this simple contrivance in drawing will 

 find it a material aid in many cases. Its frequent usefulness on other occa- 

 sions, as a light-moderator for low power examinations, will insure it a per- 

 manent place on the work-table. 



WURZBUFG, Germany, March, 1888. 



Solution of Carmine in Sodium Carbonate.* G. Cuccati. — Sodium 

 carbonate 20 gms., water 100 c.c, heat and add pulverized carmine 5 gms. ; 

 then boil, and after the solution has become cold add 30 c.c. of alcohol. 

 Allow the mixtui"e to stand for twenty-four hours, filter and add, little by 

 little, 300 c.c. of water acidulated with 8 c.c. of a 3 per cent, solution of 

 hydric acetate, then 20 gms. of chloral hydrate. After staining, the sections 

 are decolorized in a i per cent, solution of hydric chloride in alcohol. 



* 3 f. w. Mikros., iv. p. 50, 1887. 



