58 The Microscope. 



lutely essential to possess a microtome. It saves an immense 

 amount of time and patience, and does work which cannot possibly 

 be done by hand. The writer has found the microtome made by 

 Schanze, of Leipsic, as the most satisfactory for general work. 

 Several American manufacturers make microtomes on the same 

 model and which serve equally well. (See page 214, vol. VII.) 

 10. Glassware and china. Under this head come a large number of 

 articles. If one wants to luxui'iate, let him do so here. Glass 

 boxes with tightly-fitting covers and of various sizes, china bowls 

 and saucers, bell- jars, etc., are all necessary. 



Reagents. — All reagents should be kept in glass-stoppered 

 bottles, and before using the contained chemical the portion around 

 the stopper should be carefully cleansed from all dust. The 

 following reagents will be required for ordinary work : Alcohol, 

 95-97 per cent. — absolute alcohol is much more expensive and no 

 more useful than that of 95 per cent, strength ; dilute acetic acid ; 

 caustic potash, 50 per cent, solution ; hydrochloric acid ; nitric 

 acid; sulphuric acid; "normal" salt solution (^ per cent, 

 solution of Na CI. ) ; distilled water in large quantity ; glycerin ; oil 

 of cloves ; turpentine ; Canada balsam, thinned with chloroform ; a 

 cleaning mixture for slips and covers, composed of equal parts of 

 benzol, turpentine and benzine ; ammonia carmine ; Friedliinder's 

 solution of hfematoxylin ; a solution of picro- carmine ; picric acid 

 in ciystals ; nitrate of silver, ^ per cent, solution, to be kept in a 

 dark glass bottle or one wrapped in blue paper ; tincture of iodine. 



The above list is rather extended, but contains nearly every- 

 thing required. The formulae for the stains can be found in the 

 Elementary Department of last year. In making up the hsema- 

 toxylin stain, use the crystals rather than the extract. The result 

 will be certain and the solution much clearer and more permanent. 



The ammonia-carmine may have an excess of ammonia. The 

 usual proceedure is to drive ofP the ammonia. Though this insures 

 a truer carmine tint it lowers the value of the solution as a stain. A 

 slight excess of ammonia ( and, in some cases, a large excess ) will 

 cause the stains to work more rapidly and completely. 



RUDIMENTS OF PRACTICAL EMBRYOLOGY.* 



W. p. MANTON. 



§ 3. In order to develop the germ in the egg, an incubator of 

 some kind is necessary. For this purpose we may utilize a setting 

 hen — the cheapest, but most unsatisfactory method — or a simple 



♦Copyright, 1883. 



