340 SUMMARY OF CURRENT RESEARCHES RELATING TO 



B. Collecting, Mounting and Examining Objects, &c. 



Modified Hardening Process for the Central Nervous System.*— 

 It is difficult to obtain the human brain in a fresh condition, 36-48 

 hours generally elapsing after death before it is available for examina- 

 tion. Giacomini proposes the following process to give the prepara- 

 tion greater firmness and elasticity. 



After the preparation has been hardened in Miillcr'a fluid, in- 

 stead of putting it in alcohol it is placed for some days in a 5 per 

 cent, sublimate solution, which is renewed every day until it is no 

 longer coloured. If left in the fluid too long, the preparation becomes 

 black, or if not long enough, small black points will appear. It is 

 very elastic and firm, and very thin sections can bo cut, and it stains 

 well with ammonia-carmine. 



Preparing Meroblastic Ova.t 



The following are C. Kupffer's methods : — 



Reptilian Ova. — The ova taken from the oviduct are opened in a 

 dilute solution of • 1 per cent, osraic acid and the albumen removed 

 as far as possible. The osmic acid is then turned off and a weak 

 1/3 per cent, solution of chromic acid added for 24 hours. With 

 a fine pair of scissors the germinal area is cut round just outside its 

 margin, and after it has been completely encircled with the incision, 

 floated carefully off from the body of the yolk. The yolk and acid 

 are next removed, and a copious sujiply of clean water added, which 

 must be several times renewed. It is then put for 3 hours in 

 Calberla's fluid ({i a glycerin, water, and absolute alcohol in equal 

 parts), hardened in 90 per cent, alcohol, and stained in Bohm's 

 carmine acetate for 24 hours. 



Teleostean Ova (T./ario). — Chromic acid (1/3 per cent.), 24 houi-s. 

 Distilled water for 2 hours. The egg-membrane expands, and may 

 now be easily removed. Wash in distilled water 12 hours. Absolute 

 alcohol, glycerin, and aq. dist. in equal parts for 4 hours. Absolute 

 alcohol. Bohm's carmine acetate (1 to 2 days). Mixture of water 

 and glycerin (equal parts), and 1/2 per cent, hydrochloric acid, for a 

 few minutes. Wash in water (4 to 5 hours). Absolute alcohol 

 (12 hours) preparatory to imbedding in paraffin. 



Karyokinetic figures are brought out with great distinctness. 



Hydrogen Peroxide as a Bleaching Agent.J — J. D. Hyatt finds 

 this to bo very successful for insects. A flea, for instance, thus bleached 

 shows the heart and all the other internal organs clearly and per- 

 fectly and in their proper place. The respiratory system is parti- 

 cularly fine. In the process of decoloration by liquor potassae, these 

 delicate structures are either partly or quite destroyed. 



* ' Fascia dentata del grande ippocampo nel cervello umano.' Torino, 1883, 

 pp. 66-7. Zeitschr. f. Wiss. Mikr., i. (1884) pp. 449-51. 



+ Arch. f. Anat. u. Physiol. (Anat. Abtheil.) 1882, p. 4. Cf. Amer. Natural., 

 xix. (1885) p. 332, and Lee's Microtoraists' Vade Mecum, 1885, p. 316. 



X Journ. New York Micr. Soc, i. (1885) p. 22. 



