1889.] MICROSCOPICAL JOURNAL. 267 



Sodium carminate (carminsaures Natron) appears to have been 

 introduced in the dry powdered form, in 1882, by Maschke*, of Bres- 

 lau ; formerly the salt was- obtainable only in that city, but later it 

 found its place on the list of Dr. G. G rubier , of Leipzig, from whom 

 my recent supplies were obtained. 



The peculiarity of the method followed by Dr. Schultze consisted 

 not in the employment of this particular carmine salt (for Gierke had 

 used it quite extensively in his experiments), but in the avoidance of 

 all washing or soaking in water or weak alcohol before staining by 

 transferring the tissue directly from Midler's fluid into the stain, 

 where it remained until sufficiently colored, when it was washed out in 

 alcohol of gradually increasing strength. The uncertainty of satisfac- 

 tory results, which attended Schultze's first trials, disappeared with 

 the precaution of leaving the tissue at least two months in the Midler 

 before staining, a prolonged stay in the fluid doing no harm, providing 

 care be taken to renew it on the appearance of turbidity. 



My own experience teaches that tissues preserved in and transferred 

 directly from Erlicki's fluid, or from ammonium bichromate, stain 

 equally as well as those from the Muller — probably any of the bichro- 

 mate solutions will answer. The block of tissue to be stained is placed 

 in say 20 to 25 cc. of a freshly prepared one per cent, aqueous solution 

 of the sodium carbonate, and allowed to remain until deeply colored 

 throughout, which, with the strength of stain indicated, and with 1 cu. 

 cm. blocks of tissue, usually requires 48 hours ; as the solution tends 

 to decompose after a few days, the addition of a crystal of thymol is 

 desirable. After staining, the tissue is washed in 70 alcohol until all 

 excess of color has been discharged (iS to 24 hours), after which it is 

 ready for the stronger alcohols necessary for imbedding. 



The excellent results obtained by this use of the sodium carminate 

 naturally suggested the trial of the closely allied ammonia carmine 

 under similar conditions ; the latter substance Schultze found to work 

 very well with Midler's fluid, the staining being brilliant and well 

 differentiated. My use . of the ammonia carmine has been, likewise, 

 highly satisfactory, and additional tissues from Erlicki's fluid are found 

 to stain especially well. The solution employed is composed of car- 

 mine, 2 grm. ; strong aqua ammonia, 5 grm. ; distilled water, 50 cc. 

 The solution should be lightly covered and allowed to stand until all 

 the ammonia has escaped ; for use it is diluted with an equal volume 

 of water. The tissues are transferred directly from either the Midler 

 or Erlicki into this quite strong solution, and are thoroughly stained in 

 twenty-four hours ; borax-carmine and alum-carmine gave failures 

 under similar conditions ; likewise, the results here described are not 

 to be obtained when the tissue has been subjected to the prolonged 

 action of water or alcohol. 



Comparison of these carmine stains shows that in general their re- 

 sults are about equal ; the ammonia salt stains, however, rather more 

 rapidly, with better penetration, and yields the more brilliant tint, but 

 gives a less crisp differentiation of axis-cylinders and cell processes than 

 is seen in successful stainings with the sodium carminate. The pre- 

 cipitation which sometimes takes place with the latter solution I have 

 never seen with the ammonia stain. 



*Gierke: Fiirberei zu mikroskopischen Zwecken; Zeitschrift fur wissenschaft. Mikroskopie, Bd. I, 



