1880.] 



MICKOSCOPICAL JOUKNAL. 



145 



in spirit, when more of the first 

 color generally comes out. When 

 it is quite clean, it is ready for 

 mounting in the usual way. This 

 is a very good process for double 

 staining, and if the section is of the 

 same thickness throughout, the 

 staining will be perfectly even, and 

 each color will have picked out 

 those tissues for which it has a 

 special affinity. 



To stain with more than two 

 colors is much more difficult, as 

 they so often combine and produce 

 an entirely different color uniform 

 throughout. I have obtained the 

 best results from chloride of gold 

 or picrocarmine with the anilines 

 just mentioned. 



The specimen of a rat's tail was 

 first stained with chloride of gold 

 in the usual manner, and then sub- 

 mitted to the aniline process I have 

 ah'eady described. 



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 pre- 

 pared. 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 sa}' that it does equally well in 

 every other tissue as far as I have 

 tried it. But its great utility con- 

 sists of, I think, in its power to dif- 

 ferentiate glandular structures ac- 

 cording to their secretions. For 

 instance, in the section of dog's 

 tongue the ordinary mucous gland 

 will be found to have taken on a 

 purple color, while serous glands 

 which supply the secretions to the 



taste-organs stain a totally different 

 color. Again, in an examination 

 I made lately in a case of Dysid- 

 rosis I was able to stain the duct of 

 the sweat-gland an entirely different 

 color from the surrounding tissues, 

 and so demonstrate its relation to 

 the vesicles. For minute structures, 

 such as the dividing nuclei of ger- 

 minating 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 in- 

 jecting them, and shows the vessels 

 in their natural state, without the 

 bulges in them depicted by some 

 writers, which are caused by the in- 

 jection mass unduly distending 

 them. It also shows the amyloid 

 substance in amyloid degeneration 

 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 in- 

 stance, as unless this is done no 

 good result can be obtained from 

 any staining process. Every speci- 

 men properly prepared will bear 

 the highest magnifying power that 

 can be applied to it, and will show 

 plainly the structure of each epithe- 

 lial cell, muscular fibre, or other 

 element of which it may be com- 

 posed, and it is utterly impossible 

 to make a good specimen unless it 

 has been first properly hardened. 



o 



An Undescribed Point in the 

 Histology of the Foetal Lung.* 



BY PROF. LESTER CURTIS, A.B., M.D. 



During the whole of one's life 



* Read before the State Microscopical 

 Society of Illinois. 



