1094 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Illustrating method of preparing the 

 frog's heart. V, ventricle ; L A, left 

 auricle ; P, auriculo-ventricular open- 

 ing ; 1st L and 2nd L, first and second 

 ligatui-es; C, cannula. 



quantity of blood, gradually followed by the gelatin, issues from tbe 

 auriculo-ventricular opening. (5) When the gelatin begins to run 



pretty clear, the second ligature is 

 Fig. 259. fastened and the syringe contain- 



ing gelatin is replaced by another 

 containing a red plaster of Paris 

 injecting mass. The latter drives 

 the gelatin contained in the 

 arteries before it as far as the 

 capillaries, thus completely filling 

 the venous system. When the 

 gelatin is thoroughly cooled the 

 animal is ready for dissection. 



This method can be applied 

 with considerable ease to all the 

 smaller animals, such as frogs, 

 lizards, and pigeons, in prepara- 

 tion for class-work or investiga- 

 tion. Its advantages are nume- 

 rous. Among its disadvantages 

 may be mentioned the fact that 

 alcohol cannot well be used as a 

 preservative, because it dehy- 

 drates the gelatin, causing it to 

 shrink and break up the veins. 

 This difficulty is entirely obviated, 

 however, by the use of Wickersheimer's fluid, in which the injection 

 remains perfect for an indefinite time. 



New Methods of Preparing Carmine Staining Fluids.* — Sig. G. 

 Arcangeli states that the unsatisfactory results and the instability of 

 the ordinary carmine stains, induced him to try other methods, and 

 he has obtained excellent results by the following modifications. 



1. Boil together 100 grms. distilled water, 4 grms. boric acid, and 

 50 centigrms. carmine for about 10 minutes. Filter when tepid. The 

 fluid gives a beautiful cochineal-red stain, much resembling that of 

 eosin. The nuclei of vegetable tissues attain their maximum of 

 coloration in about twenty-four hours. The cutaneous epithelium 

 and muscular fibres of Bana esculenta stain well. It is necessary to 

 be aware that the sections should not be washed more than twice or 

 thrice in water, and should be then transferred to alcohol, which 

 seems to set the stain. 



2. Another carmine stain, which gave the best results, was obtained 

 by boiling for about ten minutes 100 c.c. of a saturated solution 

 of alum, 2 grms. of boric acid, and 25 centigms. of carmine. The 

 fluid so obtained is of a fine violet-red colour, and stains the nuclei of 

 animal and vegetable tissues in about twenty-four hours, and accord- 

 ing as the sections are placed in an alcoholic or aqueous solution of 

 the stain, so is the greater or less rapidity of its action. When used 

 in an alcoholic solution the staining is rapid, and the whole of the cell 



* Atti Soc. Toscana Sci. Nat., Proc. Verb., iv. (1885) pp. 233-7. 



