1092 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Czokor's alum-cocliineal * is an exceedingly convenient stain for 

 such purposes, as it penetrates an object of considerable size readily, 

 and differentiates admirably. Thus a Limax may be left in the fluid 

 twenty-four hours, afterwards washed in water and the excess of 

 colouring matter removed by 70 per cent, alcohol before it is trans- 

 ferred to stronger alcohol. Sections of tissues stain in the fluid in 

 from two to three minutes to two to three hours, according to the , 

 method of hardening that has been adopted. The fluid is prepared 

 as follows : — Eub up 7 grm. of cochineal with an equal quantity of 

 burnt alum in a mortar, add 700 c.c. of water, and boil down to 

 400 c.c. Add a trace of carbolic acid, and filter. 



Bismarck brown in concentrated solution in water or 70 per cent, 

 alcohol also stains well in toto ; there is no danger of over-staining, 

 as the excess of colour is removed by alcohol. It is particularly to 

 be recommended where cartilaginous parts are to be studied, or where 

 the sections are to be photographed. 



Schallibaum's collodion and clove-oil mixture (one volume of the 

 former to three of the latter) is excellent for sticking the sections to 

 the slide. Although it is possible by this method to stain the sections 

 on the slide in either watery or alcoholic media, much time is saved, 

 and on the whole more satisfactory results obtained by staining the 

 objects previously in toto. The collodion medium stains slightly in 

 anilin colours, if staining on the slide be resorted to. 



The study of a slide containing a large number of sections may, 

 in certain cases, be much facilitated by having a photograph of the 

 slide enlarged two or three times by means of an ordinary view-lens. 

 Such an enlargement is frequently sufficient to indicate where an 

 organ appears or disappears in a series, and thus to save time in the 

 study of the individual sections. 



Series of Sections. Thickness of Sections. f — Dr. E. v. Lenden- 

 feld considers that there should always be continuous series of sections 

 cut and mounted, one after the other. For certain things, however, 

 and particularly for a preliminary investigation, this is not necessary 

 to such an extent as in others, and it will save time, trouble, and 

 material, if in such a case every second section is cut thick and thrown 

 away, and every other cut to the required fineness and mounted. 



As to the thickness of sections— -a point on which a great deal 

 depends— the mutual position of whole organs or groups of cells can 

 generally be ascertained much better by means of thick sections and 

 low powers, than by means of very fine sections. For histological 

 details, however, a section is rarely too fine. 



For an investigation into the structure of a rare and valuable 

 specimen, a continuous series of sections may be recommended, which 

 are alternately as thin as they can be made, and of medium thickness, 

 say • 005-0 • 02 mm. 



Fol's Injection-table. J — Dr. H. Fol describes the table (fig, 258) 

 for injecting devised by him. (The fig. is a cliche of the original, 



* See this Journal, ii. (1882) p. 42fi. 



t Proc. I.inn. Soc. N.S. Wales, x. (1885) p. 32. 



% Fol'd Lehrbuch d. Vergl. Mikr. Anat., 1884, p. 25 (1 fig.). 



