236 SUMMARY OF CURRENT RESEARCHES RELATING TO 



acid for 2 or 3 days. They were then dissociated with needles, and 

 stained with acid fuchsin. 



The most satisfactory results were obtained from vom Rath's fixa- 

 tive, and the Heidenhain iron-hsematoxylin stain. The formula for 

 vom Rath's fluid is 200 c.cm. saturated solution of picric acid, 1 grm. 

 platinum chloride dissolved in 10 c.cm. of water, 2 c.cm. glacial acetic 

 acid, 25 c.cm. of 2 p.c. osmic acid. In this mixture embryo chicks were 

 kept for 3 days or more, the fluid being once changed. They were then 

 washed for a minute in two changes of methyl-alcohol, and placed for 

 from 24-48 hours in a 0"5 p.c. solution of pyrogallic acid. They were 

 then passed through graded alcohols up to absolute, cleared in xylol, and 

 imbedded in paraffin. No further treatment was required for the 

 sections, though it was found advisable to leave the balsam uncovered. 



The iron-hsematoxylin was used after fixation in Zenker's fluid, or 

 in saturated corrosive sublimate to which 1 p.c. glacial acetic acid had 

 been added. 



Other stains used were brazilin and Delafield's hematoxylin. 

 Golgi's impregnation method and intra vitam staining with methylen- 

 blue were not successful. Van Gieson's was used for studying the 

 formation of the sheath of Schwann. A combination of iron-hsematoxylin 

 and van Gieson brought out the cytoplasmic processes of the cells 

 accompanying the nerve-fibres, as well as those of the mesodermal cells. 



Demonstrating the Connection between Epidermis and Cutis in 

 Saurians and Crocodiles.* — F. Krauss fixed pieces of skin in Carnoy's 

 fluid, saturated solution of sublimate, picro-sublimate-acetic acid, Flem- 

 ming's fluid, and Zenker's fluid. Decalcification was effected with 5 p.c. 

 trichlor-acetic acid, or with nitric acid alcohol (1-4). The fixed material 

 was imbedded in celloidin or in celloidin-paraffin. To obtain thin 

 sections (3-4 fx) it was necessary to brush the section-surface over with 

 mastic. This procedure could be used only with the paraffin sections ; 

 for the celloidin-paraffin, thick gum arabic solution was used. When 

 gum was used, the sections stuck on the slide had to remain in water a 

 long time to remove the gum completely. 



The sections were stained with alum-carmin-hsematoxylin, by van 

 Gieson's, Unna's, and Weigert's methods. The following modifica- 

 tion of Weigert's method gave good results : alcohol-methyl-violet 

 solution and anilin-water, 15-30 minutes ; wash in salt solution, then 

 iodo-potassic iodide solution for 30 seconds or 15 minutes, according to 

 the effect desired (epithelial staining or collagen), 10 p.c. aqueous solu- 

 tion of tannin for 3-5 minntes ; dry on blotting-paper, and decolorise 

 in a mixture of xylol, 4 or 5 parts, and anilin oil, 1 part. 



The foregoing procedure may be preceded by alum-carmin. 



The elastic fibres were stained by Weigert's, or by the Unna-Tanzer 

 method. 



Studying Sperm-Cells of Decapods.+— N. K. Koltzoff found that 

 the best preservative fluids were sublimate-acetic acid (5 p.c), or subli- 

 mate alone. Fresh and salt water were used as solvents. Satisfactory 



* Arch. Mikrosk. Anat., lxvii. pp. 319-63 (2 pis. and 14 figs, in text), 

 t Tom. cit., pp. 364-572 (5 pis. and 37 figs, in text). 



