ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 529 



(3) Picrocarmine and Logwood. — Stain the sections first with 

 picrocarmine, and after staining wash them in water slightly acidu- 

 lated with acetic acid. Stain them with dilute logivood solution till 

 they assume a lilac tint. Wash them, and mount in glycerine or 

 dammar ; the great point is to avoid overstaining the sections with 

 the logwood. This method does very well for skin, scalp, developing 

 bone, and the non-strij)ed muscular fibres of the mesentery of the newt. 



(4) Picrocarmine and an Aniline Dye. — Dr. Stirling has tried a 

 great variety of the aniline dyes, but finds none of them so good, at 

 least for gland tissue, as iodine green ; it is used in the form of a 

 1 per cent, watery solution. Stain the tissue in picrocarmine, wash 

 it in water acidulated with acetic acid, and then stain it in a solution 

 of iodine green. This solution stains rapidly, and care must be taken 

 not to overstain the tissue. Rapidly wash the section in water, and 

 mount it in dammar. The section must not be left too long in spirit 

 before cleaning it with clove-oil, because the spirit dissolves the green 

 dye. Specimens doubly stained in this way have been preserved for 

 many months, and students succeed in the process with the best 

 results. Few methods yield such good results and are so instructive 

 for the purpose of teaching. All preparations stained with iodine 

 green must be mounted in dammar. 



(5) Picrocarmine and Iodine Green — Foetal Cancellous Pone, — 

 Stain a section of the cancellated head of a foetal bone in picrocar- 

 mine, and after washing it, stain it with iodine green and mount it in 

 dammar. All the newly formed bone is red, but in the centre of each 

 of the osseous trabeculae the residue of the calcified cartilage on 

 which bone is deposited is stained green. ISTo method differentiates 

 so clearly this marked difference in the constitution of these trabe- 

 culse. Many of the bone corpuscles are stained green. 



Ossifying Cuticular Cartilage, Posterior part of the Tongue, 

 Peyer's Patch, Solitary Glands, Trachea, and Bronchus are also dealt 

 with. In the case of the Skin, double stain a vertical section preferably 

 from the sole of the foot of a foetus. The cuticle and superficial 

 layers of the epithelium are yellow, the stratum (rete) Malpighii is 

 green, and one sees most admirably the continuation of these cells 

 into the ducts of the sweat-glands, which are themselves green and 

 form a marked contrast to the red-stained connective tissue of the 

 cutis vera, through which they have to ascend to reach the surface. 

 The outer layer of the grey matter of the Cerebellum with Purkinje's 

 cells is, when double stained, red, while the inner or granular layer 

 is green. 



(6) Logioood and Iodine Green does best for tlie mucous glands of 

 the tongue (green), while the serous glands take on the logwood 

 stain. 



(7) Eosin and Iodine Green. — Eosin is used as the ground colour. 

 Stain the tissue in an alcoholic solution of eosin, which will stain it 

 very rapidly, usually in a few seconds, AVash the section thoroughly 

 in water acidulated with acetic or hydrochloric acid (1 per cent.), and 

 then stain it with iodine green. This combination does very well for 

 developing bone and for the cerebellum. 



