ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1055 



The new method consists in a series of manipulations requiring only thirty- 

 five minutes for their completion. The following is a list of the reagents, 

 together with the length of time and the order in which each is to be 

 used : — 



Wins. 



1. Corrosive sublimate (concentrated solution) H 



2. Distilled -water 1 



3. Absolute alcohol 5 



4. Distilled water 1 



5. Haematoxylin (1/2 per cent, alum solution, to which, for every 100 ccm. 



emploved, 20 drops 5 per cent, alcoholic solution have been added) . . 6 



6. Distilled water 1 



7. Nigrosin (1/2 per cent, water solution) 1 



8. Distilled water . . ^ 



9. Eosin (1 gr. eosin dissolved in 60 ccm. alcohol ; 140 ccm. distilled 



water) 2 



10. Alcohol 5 



11. Oil of cloves 1-2 



12. Xylol. 



13. Canada balsam (diluted with xylol until it readily flows). 



As receptacles for these fluids, each person has upon his table thren 

 shallow glass dishes with flat bottoms, so large that a slide may be easily 

 put in and taken out of them. Into the first of these is poured corrosive 

 sublimate, into the second distilled water, and into the third absolute 

 alcohol. It is necessary either to label the dishes or to place the two not 

 at the moment in use at one side. For the colouring fluids bottles are used 

 whose stoppers serve at the same time as droppers or pipettes. The most 

 convenient form is the glass stopper, which broadens into a funnel, closed 

 by a rubber membrane. For oil of cloves, xylol, and Canada balsam wide- 

 mouthed bottles are used. In the first two bottles are brushes ; in the last, 

 the ordinary glass rod. Other necessary utensils are a glass rod, sharp- 

 pointed scissors, clean slides and cover- slips, filter-paper, twine or coarse 

 thread, a small bottle of absolute alcohol, a sharp, clean needle, a fine clean 

 rag, and a hand-towel. 



Aside from these, a board, 5 by 15 in., with two pairs of holes, large 

 enough for a piece of tape to pass through double, is an essential help. 

 The first pair of holes should be 4 in. distant from the second, and the two 

 holes of each pair 1^ in. apart. The tape should be so passed through the 

 holes that there will remain upon one side of the board loops, on the other 

 long ends, by which, upon passing the extremities of the frog through the 

 loops, one may easily and firmly tie the frog upon the board. Such 

 preparation is necessary, otherwise the manipulations cannot follow one 

 another quickly enough. After these preliminaries have been completed, 

 the labelled bottles being placed within reaching distance, the distilled 

 water and alcohol in front of these, and the corrosive sublimate nearest of 

 all, we are ready to bind our frog upon the above-mentioned board and 

 begin our preparation. We make use of the frog for this purpose at first, 

 since its blood coagulates less quickly than that of mammals. The vena 

 femoralis, which may be seen as a dark blue line below the knee-joint on 

 the inner side of the leg, having been snipped, we quickly bring with a 

 glass rod a drop of the blood which comes from the wound upon a slide 

 previously moistened by the breath, and throw the whole into the dish of 

 sublimate for six minutes. If a little care is taken to spread out the drop 

 of blood in putting it on the slide, the result is more satisfactory. Brought 

 from the sublimate into the dish of water, we find that the greater part of 

 the blood adheres to the slide. The superfluous sublimate being washed from 

 the preparation during the moment that it remains in the water, we next 



3 z 2 



