ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 291 



which they should lie for half an hour, protected from the light. 

 Again taken out and washed, they are put in 50 cm. of distilled water, 

 acidulated with 1 per cent, of formic acid, and kept in the dark for 

 twelve hours, and then for as many exposed to sunlight. Next they 

 are put in a small glass and wetted with formic acid, so as to cover 

 them, and again kept in the dark for twenty-four hours. Finally, 

 the acid is removed, and they are washed in distilled water, which is 

 in its turn removed and replaced by Price's glycerine. 



Thus treated the fibres are tinted in different colours, some in 

 a more or less deep blue, others in an intense or light violet, and 

 others, again, in a cinnabar red or dark reddish brown. The double 

 chloride is, in the author's view, preferable to the use of chloride of 

 gold, because the former is less uncertain in its action, and does not 

 give rise to the disagreeable precipitates produced by the latter when 

 it comes in contact with the " organized and nearly living parts." 

 The method has been successfully used with the cornea of frogs, 

 birds, and mice, and other parts rich in nerves. 



Monobromide of Naphthaline for Histological Preparations.* 

 — Dr. M. Flesch refers to the fact that this fluid has apparently not 

 been used in histology, although it has proved to have important 

 advantages for diatoms. Whilst he has not himself arrived at results 

 of a special kind (on the contrary, in many cases which justified a 

 hope of success the result was negative) yet he thinks it desirable to 

 call attention to the medium as it is not improbable that in the case of 

 objects in which everything is not revealed by staining, many parts 

 may be seen better in monobromide of naphthaline than in other 

 media. 



The preparations must be very carefully dehydrated as the slightest 

 trace of water produces cloudiness. They can be mounted either direct 

 from absolute alcohol, or after being passed through oil of turpentine 

 (creosote and oil of cloves are less suitable). For cementing, either 

 wax or lac-varnish or thickened Yenice turpentine. 



Dr. Flesch suggests further experiments to determine whether or 

 not monobromide of naphthaline improves the recognition of minute 

 structures such as fine wrinkles in skin, small granulations, &c. 



Sulpho cyanides of Ammonium and Potassium as Histological 

 Eeagents.l — Prof. W. Stirling calls attention to the value of the 

 sulphocyanides for revealing the presence and arrangement of the 

 intranuclear plexus of fibrils in coloured and colourless blood-cor- 

 puscles. For this purpose a drop of a 10 per cent, solution of either 

 agent is added to a drop of the blood of a newt or a frog. After a 

 time the htemoglobin becomes quite discoloured or removed, and 

 remarkable changes take place in the nucleus ; it swells up, becomes 

 more distinct, and shows in its interior an exquisitely arranged intra- 

 nuclear plexus of fibrils. This plexus can be stained with fuchsin or 

 eosin, and kept for a long while. 



The solutions are also admirable " dissociating " media for iso- 



* Zool. Anzeig., v. (1882) pp. 555-6. 



t Journ. Anat. and Phybiol., xvii. (1883) p. 207-10, 



u 2 



