ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 957 



cerebral cortex, and gastric mucous membrane, stained with Klein's 

 cochineal fluid. The preparation of and modus operandi with this 

 fluid are exceedingly simple : 1 per cent, of alum and cochineal in 

 distilled water are boiled to four-sevenths of the original volume ; when 

 cool, a few drops of carbolic acid are added, and the liquid filtered. 

 Sections will stain well in three or four hours, but will not be injured 

 if left twenty-four hours. They require nothing but washing in distilled 

 water. The branching processes of Purkinje's cells in the cerebellum, 

 the connection of the kite-shaped cells of the cerebral cortex, and the 

 " chief " and " investing " cells of the gastric mucous membrane 

 were rendered especially evident by this method. 



Purpurine for Staining Fcetal Vertebrae.* — Dr. Harvey also 

 showed a section of foetal vertebrse stained with purpurine. AH the 

 effects for which double-staining had been so much recommended of 

 late, in studying the process of ossification in cartilage, are brought 

 out by this dye. The cartilage matrix remains unstained, the new 

 territories of bone-substance assume a distinct though somewhat pale 

 hue, while all the cells (cartilage-cells, bone-cells, osteoblasts, and 

 marrow-cells) become brilliantly stained. 



Cements and Cementing.']' — Mr. C. E. Hanaman, after an expe- 

 rience of more than twelve years, during which he has used nearly 

 every kind of cement that has been suggested in the journals and 

 books published in England and America, has arrived at the con- 

 clusion that two, or at most three, cements are capable of ensuring the 

 preservation of an object in any medium the microscopist will find it 

 necessary to employ. These are gold-size (Windsor and Newton's), 

 the ordinary dammar mounting medium, and possibly, for occasional 

 use, the dammar medium to which a small proportion of a solution 

 of rubber in naphtha has been added. 



Dr. Seller and others have directed the student to apply his 

 cements in several coats, using great care in holding the brush, and 

 as to the quantity of cement in the brush. The author saves himself 

 much of the time required by such methods of manipulation, by 

 putting on the cement in a broad band over the junction of the cover 

 with the slide, and then, spinning the turntable as rapidly as pos- 

 sible, running the cement into a narrow band, in its proper place, by 

 holding a knife-blade first on the slide and then on the cover, in such 

 a manner as to cause the cement spread out by the brush to heap 

 itself up into a narrow but perfect ring. One coating of cement thus 

 put on is equal to three or four coats by the other method, while the 

 polish of the ring far sm-passes in perfection the brush-made ring. 



If it is desired to colour the ring, instead of using anil in mixed 

 with the cement, the more transparent of the water-colours are useful. 

 The manner of their application is this : After the dried balsam or 

 dammar has been thoroughly cleaned from the slide and cover, the 

 preparation is placed on the turntable, and a narrow ring of the 

 water-colour applied. This will dry quickly and look somewhat 



* Ann. and Mag. Nat. Hist., viii. (1881) p. 234. 

 t Amer. Mon. Micr. Journ., ii. (1881) pp. 143-4. 



