ZOOLOGY AND BOTAXY, MICROSCOPY, ETC. 895 



When the bone is softened, the tail is to be soaked in water to 

 remove the acid and reharden in spirit. 



Transverse sections are cut from the tail and stained in the 

 ordinary borax-carmine solution ; when suflBciently stained they are 

 transferred to methylated spirit, and then placed in a mixture of five 

 parts spirit and one part hydrochloric acid ; from this they must be 

 removed as soon as they attain a brilliant scarlet tint, and be again 

 placed in spirit until no trace of acid remains. The sections are then 

 to be stained in sulph-indigotate of soda — two drops of a saturated 

 aqueous solution of which are added to one ounce of spirit — and in 

 this the sections should remain for from four to six hours. They 

 are then to be finally and carefully washed in spirit, cleared in oil of 

 cloves, and mounted in Canada balsam. 



Demonstrating Spindle-shaped Bodies in the Yolk of Frog's 

 Ova.* — Dr. 0. Hertwig states the best method is to place the ovary 

 for two or three minutes in a mixture of • 3 per cent, osmic acid and 

 • 1 per cent, acetic acid, and then in order to prevent over-blackening 

 transfer to iodized serum or bichromate. Osmic acid causes ova to 

 coagulate homogeneously, so that they are transparent. Very dilute 

 acetic acid on the other hand clearly shows up the contours of 

 germinal vesicle and nucleoli. Excessive blackening by osmic acid 

 may be removed by peroxide of hydrogen. Thus treated, ova retain 

 all their details after six months. Only teasing out is required. 



Microscopical Technique of the Eye.f— Dr. E. Warlomont 

 describes the method of preparing specimens of eyes for microscopical 

 examination which is used at the Moorfields Ophthalmic Hospital. 

 The whole eye is placed in Miiller's fluid for 3-4 weeks, and then cut 

 with a sharp knife into two symmetrical parts, which are washed in 

 water to remove the yellow colour. The decoloration is hastened 

 by placing them for several minutes in a 1 per cent, solution of 

 chloral. They are then placed for a day in ordinary alcohol, and 

 transferred to absolute alcohol for 24 hours. They are next 

 placed for 24 hours in celloidin dissolved in equal parts of sul- 

 phuric ether and absolute alcohol, and laid in a paper box, which 

 is filled with the celloidin solution. When this has become 

 changed into a gelatinous elastic mass, it is placed in ordinary 

 alcohol (70-80), in which it acquires the necessary hardness, and in 

 which it can be preserved indefinitely. The sections are cut with 

 Katsch'g microtome beneath alcohol, stained with Ehrlich's logwood 

 or other solution, washed in water and alcohol, clarified in oil of 

 bergamot, and mounted in balsam. 



Preparing Eyes of Gasteropods.t — Concentrated solution of per- 

 chloride of mercury is found by Dr. C. Hilgor to keep the rods in good 

 condition for hardening in Miiller's fluid. Picric acid or alcohol may 

 bo used. The best stain is hematoxylin. First overstain, then docolo- 



* Morphol. Jahrb., x. ri884) pp. 337-43 (1 pi.), 

 t Bull. Soc. Belg. Micr., xi. (1885) pp. 201-8. 

 J Morphol. .Jahrb., x. (1884) pp. 351-71 (2 pis.). 



