714 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and flowing together covers the blade with a layer of water along its 

 whole length, even when it is lightly smeared with oil or has become 

 greasy from the imbedding mass. It should, however, be kept in a 

 horizontal position, or better somewhat inclined to ensure the water 

 flowing over it. A vessel is placed under the hand to catch the water 

 and also the sections which can be floated off by its aid, an important 

 advantage of the instrument. If very large sections are required, the 

 tube should not be directly attached to the blade, but a few millimetres 

 above it. The section can then be floated off between the tube and 

 the blade. 



Differential Staining of Nucleated Blood-corpuscles.* — It has 

 been urged against the differential staining of histological structures, 

 that the process may induce an alteration which may be mistaken for 

 the normal condition. That this is, in many cases, true, is beyond 

 question, but Dr. A. Y. Moore considers that the exceptions are far 

 too numerous to justify it as a rule. For some years past he has 

 used a process for the double staining of nucleated blood-corpuscles, 

 which causes no alteration, except of course in colour, and as the 

 structure can be seen much better in a semi-transparent than in a. 

 more perfectly transparent body, the corpuscles thus stained offer 

 advantages for study which are not found in those left unstained. 



The fluids used for this purpose are two, viz. : — A. Eosin, 

 5 grains ; distilled water, 4 drachms ; alcohol, 4 drachms. Dissolve 

 the eosin in the water and add the alcohol. B. Methyl-anilin green, 

 5 grains ; distilled water, 1 ounce. 



The blood should be spread upon the slide, by placing a drop 

 upon one end and quickly drawing the smooth edge of another slide 

 over it. This, if well done, will leave a single layer of corpuscles 

 evenly spread over the central part of the slide. When the corpuscles 

 on the slide are thoroughly dry, which will only require a few minutes, 

 the slide should be " flooded " with stain A. This should be allowed 

 to remain on for about three minutes, at the end of which time, it 

 may be washed by gently waving back and forth in a glass of clean 

 water. Before it is allowed to dry, the corpuscles should be again 

 flooded, this time with stain B. After two minutes' exposure to this 

 fluid, the slide should be washed, as before, and set away to dry. 

 When dry, a drop of Canada balsam may be put upon the blood, a 

 cover-glass applied and the whole gently warmed until the balsam 

 spreads out properly. When hard it may be finished the same as is 

 usual with balsam mounts. 



If now examined with the Microscope, the corpuscles will be found 

 to be well stained with red, while the nuclei and " leucocytes " will 

 be a bluish-green. The granular appearance which is ordinarily seen 

 in the nuclei, now shows with a vigour and sharpness which is diffi- 

 cult of description, while the whole corpuscle is as brilliant as a newly- 

 cut ruby. 



The Editors of ' The Microscope ' (which since its commencement 

 has contained much valuable matter), call special attention to the 



* ' The Microscope,' ii. (1882) pp. 73-6 (1 col. pi.). 



