74 OTHER ANILIN STAINS. 



stain with a certain affinity for certain elements belonging to the group of 

 the connective tissues ; and that with some other colours it gives sharply 

 differentiated double stains of certain preparations. These will be mentioned 

 in the proper places. 



120. Sauregelb (Echtgelb) Tropaeolin O., Crocein, Gold Orange, 



are all of them more or less diffuse yellow or orange stains, having certain 

 affinities for certain tissues, and may occasionally be found very useful for 

 double staining, being good stains in their way (see GEIESBACH, Arch. f. 

 mik. Anat, xxii, p. 132). 



121. Iodine Green ("Hofmann's Grim ") (GEIESBACH, Zool. 

 Anz.j No. 117, vol. v, 1882, p. 406). Griesbach employs the 

 following solution : 



Crystallized iodine green . . 0' 1 gr. 



Distilled water .... 35'0 



These proportions may be varied according to the desire of 

 the operator, within limits indicated only by the observation 

 that good results can only be obtained from deep-hued solu- 

 tions. 



The objects are to be put into water for a few seconds 

 before staining. They stain instantaneously in general. 

 They are to be washed out in water, and brought into glyce- 

 rin, or dehydrated in absolute alcohol and passed through oil 

 of cloves or anise-seed into balsam or dammar. The stain is 

 not destroyed by immersion in alcohol for days. The prepara- 

 tions are apparently permanent in balsam. 



Alcoholic solutions may be used for staining, but Griesbach 

 finds no advantage in so doing. 



A nuclear but frequently diffuse stain, valuable for the 

 exceeding rapidity of its action, and for its striking power 

 of marking-out by staining in various hues the different forms 

 of tissue. For instance, in a section through the uterus of a 

 roe-deer, the epithelia are stained blue, the glands dark green, 

 and the muscle-fibres malachite green, whilst the connective 

 tissue remains unstained. 



Chromic acid objects stain well. The colour is useful for 

 double staining (see post) Chapter XIII) . 



This colour is somewhat expensive to prepare, and for this 

 reason is no longer found in commerce, having been super- 

 seded by methyl green. But the high price is no impediment 

 to the use of iodine green in histology, on account of the small 

 quantity of the substance required for staining. 



