108 MICROSCOPICAL RESEARCH IN NAPLES. 



This mixture, poured very slowly into the containing-glass, 

 often gives very good results, both for anatomical and histological 

 purposes. 



C. Nicotine and Tobacco-Smoke.—^. A solution of nicotine 

 (i g.) in sea- water (i 1.), conducted into the vessel containing the 

 animal fully expanded in a half litre of sea-water, by means of a 

 thread sufficiently large to empty the flask holding the nicotine 

 solution in the course of twelve hours. 



b. The vessel containing the animal in an extended condition, 

 covered by a bell jar in which tobacco-smoke is confined, until 

 the animal becomes completely benumbed. 



After being deprived of sensibility by either of these methods, 

 the creature may be killed in corrosive sublimate, or in picro- 

 sulphuric acid. 



D — Dr. Andres finds that in the use of chloroform, dropped 

 slowly into the water, or administered in form of vapour, macera- 

 tion usually sets in before the power of contracting is lost. Good 

 preparations of the internal parts may be obtained by injecting a 

 weak solution of osmic acid. The method of freezing has also 

 been employed with some success. For this purpose three vessels 

 are placed one within the other, the central one containing the 

 actinia, the middle one ice and salt, and the outer one cotton. 



The ice containing the congealed animal is dissolved in alcohol 

 or an acid. 



E. Maceration. — It is often important to see the cells of a 

 tissue in situ before freeing them with needles. In such cases Dr. 

 Andres proceeds as follows : — 



I. — Killed with corrosive sublimate. 



2. — Left in 25 per cent, alcohol twenty-four hours. 



3. — Soaked for a short time in a very thin solution of gum 



arabic^ then in a somewhat thicker solution, and finally 



imbedded in a very thick solution. 

 4. — Hardened in 90 per cent, alcohol. 

 5. — Thick sections prepared for dissection with needles. The 



sections are placed on a slide in water, which dissolves 



the gum. 



