664 SUMMARY OF CURRENT RESEARCHES RELATING TO 



heated to about 24"^ C, the posterior third of the uterus will require an 

 exposure of only 10 to 15 minutes. 



(1) Schneider's acid carmine is an excellent staining agent. It is 

 prepared as follows: — Ghicial acetic acid is diluted with distilled water 

 to about 00 per cent., then as much pulverized carmine is added to the 

 boiling acid as will dissolve. After filtering until the fluid becomes 

 clear, a little rectified wood-vinegar is added (one drop A. pyrolignosum 

 to 10 ccm. of the carmine solution) for the purpose of strengthening the 

 clarifying power of the mixtui-e. The younger stages may be left in 

 the dye 3 to 4 hours, the older stages 8 to 10. 



Beautiful views of the karyokiuetic figures are thus obtained, but 

 they are not permanent ; after 3 or 4 hours they begin to lose in distinct- 

 ness. Grenacher's alcohol carmine gives more durable preparations. 

 Eggs thus stained may bo improved by treatment with methyl-green 

 (2 per cent.) to which have been added a few drops of glycerin. The 

 6i)indle-fibres of the first and second amphiasters may be most success- 

 fully stained with " Modebraun " in very dilute aqueous solution. Pre- 

 parations are mounted in two-thirds glycerin. 



Boveri's Method of Preparing the Eggs of Ascaris megalo- 

 cephala.* — The following is Prof. T. Boveri's method : — 



(1) The egg-sacs are plunged for a few seconds in boiling absolute 

 alcohol which contains 1 per cent, glacial acetic acid. The eggs are 

 thus killed instantly, and at the same time the egg-membrane is rendered 

 penetrable to the reagents. The alcohol is allowed to cool gradually, 

 and after a few hours the eggs are transferred to pure alcohol, coloured, 

 and examined in glycerin or clove oil. This method shows the achro- 

 matic spindles and the chromatic equatorial plates, but not a trace of 

 protoplasmic asters. 



(2) The following mixture was used cold, with excellent results. A 

 saturated solution of picric acid is diluted with twice its volume of 

 water, and then 1 per cent, glacial acetic acid is added. The egg-sacs 

 are left at least twenty-four hours in this mixture, then washed in 

 70 per cent, alcohol, stained in Grenacher's alcoholic borax-carmine 

 (24 hours), transferred to 70 per cent, alcohol plus 1 per cent, hydro- 

 chloric acid (24 hours), and finally placed in pure alcohol. 



For examination, glycerin is preferred to clove oil. If the egg-sacs 

 are removed from alcohol to a mixture of glycerin (1 part) and absolute 

 alcohol (3 parts), and then allowed to stand until the alcohol has 

 evaporated, the eggs do not shrink. It will be found, however, that the 

 eggs are not all equally well preserved with the cold mixture, owing 

 probably to individual differences in the constitution of the membranes, 

 some being more, others less permeable to the fixing reagent. 



Isolating Foraminifera.t — Herr C. C. Keller states that Foraminifera 

 can be obtained from marl in a very short time and in a very clean con- 

 dition in the following manner. The marl is first reduced by means of 

 highly concentrated Glauber's salts. When the pulverization has pro- 

 ceeded sufficiently, the suljihate of soda is washed out and the residue 

 poured into a glass vessel in which there is a little water. The vessel 

 is then filled up with carbonic acid water, and then placed in some warm 

 spot or is warmed in a water-bath, its contents being carefully stirred up 



* Jciiaisch. Zeitscbr. f. Naturwiss.. xxi. (1887) p. 432. Cf. Amcr. Naturalist, 

 xxii. CISS8) pp. 381-2. f Zcitschr. f. Wiss. Mikr., iv. (1887) pp. 474-5. 



