ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 379 



clean water. The animals are now narcotised with (1) 2 p.c. solution of 

 hydiochlorate of coeain 3 parts, alcohol 1 part, water 6 parts ; or (2) 

 1 p.c. aqueous solution of hydrochloride of eucain. The narcotic is 

 added drop by drop until the movements slacken or almost cease, the 

 time varying from 15 minutes to several hours, according to the species. 

 The animals are next killed and fixed with ^ p.c. osmic acid, with 

 Flemming's chrom-aceto-osmic fluid, or with Hermann's platino-aceto- 

 osmic mixture, the preference heiug given to the last. One drop of the 

 fixative is sufficient. After a few minutes the animals are washed 

 ssveral times in clean water, for marine rotifers sea-water heing used. 

 The rotifers are then removed to 2h p.c. formalin, made by mixing 

 2-5 ccm. of commercial formaldehyde with 37*5 ccm. of water. In this 

 fluid they may he kept, or mounted therein in ground-out cells or in 

 shallow built-up cells. When mounting, place a drop of the formalin 

 solution in the cell and transfer the rotifers. Place another drop of 

 formalin by the side of the cell, lower the cover-slip on this drop, and 

 then push the slip cautiously and gradually over the cell. The super- 

 fluous fluid is removed with blotting-paper and the cell closed with 

 dammar gold-size cement. To do this, first run round a varnish consist- 

 ing of two-thirds dammar in benzol and one-third gold-size, then two 

 coats of pure shellac dissolved in alcohol, and finally 4 or 5 coats of 

 pure gold-size, with an interval of 24 hours for each coat.. 



(6) Miscellaneous. 



Method of Preserving Museum Specimens.* — H. Gait has found 

 the following solution to give hetter results than the Kaiserliug fluid for 

 preserving museum specimens : — Common salt 5 oz., potassium nitrate 

 1 oz., chloral hydrate 1 oz., water 100 oz. The preliminary treatment 

 consists in washing the specimen in water, and after properly trimming 

 it immersing it in methylated spirits for a time corresponding to its 

 size. 0*5 p.c. formalin may be added to the spirit. 



Method for Demonstrating the Framework of Organs, f — Dr. 

 J. M. Flint describes an extension of Spalteholz's method of demon- 

 strating the framework of organs. The pieces should not exceed 3 mm. 

 in thickness, the other dimensions being immaterial. The tissue from 

 which the piece is taken is first fixed with Van Gehuchten's fluid 

 {glacial acetic acid 10 parts, chloroform 30 parts, ahsolute alcohol 

 60 parts), or with graded alcohols. After fixation, the tissue is dehy- 

 drated and then transferred to ether, and the fat extracted in a Soxhlet 

 apparatus. When all the free fat has been removed, the tissue is 

 dehydrated in graded alcohols, and then having been again washed with 

 water, is treated with pancreatin. The process of digestion is watched 

 from time to time under the Microscope, and when digestion is complete 

 nothing but the framework remains. When this stage is reached, the 

 tissue is washed in distilled water and cleared with glycerin. The 

 framework can then be studied with the stereoscopic Microscope. 



After a study of the framework in the three dimensions, the piece 

 may be cut up for permanent preparations. The glycerin is washed 



* Lancet, 1901, ii. pp. 1334-5. 



f Johns Hopkins Hosp. Bull., xiii. (1902) pp. 48-52 (1 fig.). 



