392 Transactions of the Society. 



To stain with picrocarmine I make a dilute solution about ten 

 drops to a watch-glass of distilled water, and leave the sections in it 

 for about half an hour ; the time will vary with the tissue and the 

 manner in which it has been prepared. They are then removed to 

 plain water acidulated with a few drops of acetic or picric acid, 

 and left in it for an hour, after which they are ready for the 

 aniline process. 



This method succeeds very well in the tongue of different 

 animals, as will be seen from the specimens under the Microscope ; 

 and I can also say that it does equally well in every other tissue as 

 far as I have tried it But its great utility consists, I think, in its 

 power to differentiate glandular structures according to their secre- 

 tions. For instance, in the section of dog's tongue the ordinary 

 mucous gland will be found to have taken on a purple colour, 

 while the serous glands which supply the secretions to the taste- 

 organs stain a totally different colour. Again, in an examination 

 I made lately in a case of Dysidrosis I was able to stain the duct 

 of the sweat-gland an entirely different colour from the surrounding 

 tissues, and so demonstrate its relation to the vesicles. For minute 

 structures, such as the dividing nuclei of germinating epithelium 

 or developing spermatozoa, I think logwood is far above every other 

 stain, and when used with picrocarmine I find its effect is intensified. 



The carmine and indigo-carmine process is of great use in 

 demonstrating the blood-vessels in the web of the frog's foot, the 

 tail of the tadpole, and similar structures, as it entirely does away 

 with the necessity of injecting them, and shows the vessels in their 

 natural state, without the bulges in them depicted by some 

 writers, which are caused by the injection mass unduly distending 

 them. It also shows the amyloid substance in amyloid degenera- 

 tion of the liver to perfection, as the blue stains it alone. 



I should like to call attention to the great importance of 

 preparing all tissues properly in the first instance, as unless this 

 is done no good result can be obtained from any staining process. 

 Every specimen properly prepared will bear the highest magnify- 

 ing power that can be applied to it, and will show plainly the 

 structure of each epithelial cell, muscular fibre, or other element of 

 which it may be composed, and it is utterly impossible to make a 

 good specimen unless it has been first properly hardened. 



The following process for cleaning thin cover-glasses has proved 

 very effectual, and has reduced the breakage of •003 to about 

 half a dozen per half ounce : — First place the cover-glasses in 

 strong sulphuric acid for an hour or two ; then wash well until 

 the drainings give no acid reaction ; then place them in methylated 

 spirit, and as each glass is taken out with a pair of broad pointed 

 forceps dip it in absolute alcohol and wipe carefully with an old 

 silk handkerchief. 



