28;i The Microscope. 



2. Chrom-acetic Acid. 



Chromic acid (1 per cent.) 25 parts. 



Acetic " (1 " ) 5 " 



Water 70 '' 



The eggs are left in one of these fluids twenty-four hours, then 

 washed in distilled-water, which should be often chanofed. The egftr. 

 envelopes are next removed by the aid of needles, and the eggs are 

 ready for surface study. 



For tlie purpose of sectioning, the eggs are transferred from 

 the water used in washing to 50 per cent, alcohol, then to 70 per 

 cent., 85 per cent., and 95 per cent., leaving them twenty -four hours 

 in each grade. The last grade should be changed several times. 

 The eggs are then clarified in turpentine one to two houi-s, and then 

 placed in paraffin that melts at 50*"'C. for one-half to one hour. 



Schultze states that the success of the method depends on fol- 

 lowing precisely the directions given as to time. If the eggs remain 

 longer, either in alcohol, turpentine, or paraffin, the results may be 

 entirely unsatisfactory. If the conditions are strictly followed the 

 eggs have the consistency of the paraffin, and cut excellently, with- 

 out crumbling, in sections ^J ir mm., thick. 



For staining, borax-carmine was used, directly after washing, 

 twenty -four hoiu's. The eggs were next placed in acid alcohol of 

 seventy per cent, (five drops of the pure acid to 100 ccm. of the 

 alcohol,) to remove a part of the color. 



The first hardening-fluid does not penetrate well, and is not 

 well adapted for fixing the central part of the egg. — Arnericaii Nat- 

 uralist, June, 1887. 



Results of Miceoscopic Examination of Doubtful Minerals. — 

 Several doubtful minerals have recently been examined microscopi- 

 cally by Dr. Lacroix, (Neiies, Jahrb. f. Min., etc., 1887-1 -p. 95 >. 

 PteroUte, which Dana supposed to be an altered lepidomelane, 

 Lacroix found to be a mixture of several distinct minerals, of which 

 the most important are a black mica and a strongly pleochroic 

 pyroxene. In addition to these there are also present in pterolite 

 numerous grains of blue sodalite, rhomboheda of calcite or dolo- 

 mite, and many other minerals which are usually found in eleolite 

 syenites. Villarosite is shown to be merely a pseudomorph of 

 chrysotile after olivine. Gamsigradite has the optical properties of 

 hornblende, with a maximum extinction of 30 degrees and pleochro- 

 ism in green and brown tints. — Am. Naturali-t. 



