The Microscope. 275 



further says that there ought to be a microscope, and a good one 

 too, in every school in the land. — N. Y. Jour. Mic. 



Staining Axis-Cylinders of Medullated Nerve-Fibres. — 

 Dr. Kupffer says the axis-cylinder contains the nerve-fibrils 

 floating loose in nerve-serum. A compact axis-cylinder is an 

 artificial production. To demonstrate this he stains the nerve 

 for 24 hours in a \ per cent, solution of Osmic acid, and after 

 a thorough washing, stain with a saturated solution of acid 

 fuchsin. A transverse section will show the axis-cylinder fibrils 

 as stained points. 



Staining Desmids. — When quite fresh, wash and place in a 

 solution of chromic acid, so weak that it requires three days to 

 decolorize a large desmid. When the color has gone, wash in 

 water and stain with anilin. Fix with tartaric or weak nitric 

 acid ; then wash and mount in camphorated or carbolized water. 

 All fresh-water algae seem to do well treated in this way. — W. 

 B. Turner. 



Volvox Globator, Keeping Alive and Mounting.— -Mount in 

 a mixture of equal bulks of alcohol, water and glycerine. They 

 can be double stained by using a mixture of osmic acid, 

 anilin-green, magenta, and Hantsche's fluid. — English Me- 

 chanic. 



Properties of Malleable Iron. — The strength of a finished 

 piece of iron depends on the sectional area of the mass of iron 

 it contains. From a total sectional area of weld iron the slag 

 conclusions, and in the case of ingot iron the blow-holes, must 

 be deducted. As yet, however, microscopy has not advanced 

 far enough in this field to be of great service. 



Color of Birds' Eggs. — Both the ground color and the spots 

 are derived from the blood and not from special pigment glands. 

 The ground color is Caused by a transudation through the uterus 

 which is richly supplied with blood vessels. The spots are 

 formed by particles of pigment which are found throughout the 

 oviduct and probably arise in the Graafian follicle ; the forma- 

 tion of pigment is no doubt to be referred to a process similar 

 to that which causes the corpus luteum in the ovary of mam- 

 mals. — Zool. Anzeig. 



