CUTTING AND MOUNTING EGGS. 319 



results. For fixing the tissues the author used the mixtures recom- 

 mended by Gilson and Carnoy, and with the same result, and also 

 Flemming's fluid. (Archiv fiir Mikr. Anat., 1886, 1; also Journ. 

 Roy. Micr. Soc., 1886, 590, 1073.) 



Making Sections of Eggs. The eggs should, according to Bobret- 

 sky's method, be placed, when alive, for a short time in nearly boiling 

 water, and then hardened in bichromate of potash. They may be 

 stained in picrocarmine or in hoematoxylin, and embedded for cut- 

 ting in paraffine or coagulated albumen. Patten placed the eggs of 

 Trichoptera in cold water, raising the temperature very gradually to 

 about 80 C., or when they became hard and white; then removed to 

 20 per cent alcohol, which was increased by 10 per cent once or twice 

 a day until reaching full strength (96 per cent). They were stained 

 with Kleinenberg's hsematoxylin and a 70 per cent solution of cochi- 

 neal, and embedded in paraffine after being clarified in benzole for 

 thirty minutes. 



Witlaczil examined the embryos of the viviparous Aphides in a weak 

 salt solution (1.J- per cent), in which they live for about an hour. The 

 early stages in the development of the eggs may be best seen after 

 treatment with hydrochloric acid (3 per cent), or acetic acid, as these 

 reagents partially dissolve the yolk elements, rendering the preparation 

 more transparent; but the later stages are rendered more opaque by 

 this treatment. 



Eggs gradually hardened in alcohol and then cut and stained on the 

 slide with picrocarmiue or hsematoxylin often give good sections. 

 Kowalevsky's sections, made before the days of microtomes, were 

 cut by hand, the eggs having been, after being hardened, embedded in 

 paraffiue and cut with a razor. 



Dr. F. Stuhlman* in the examination of the eggs of insects, 

 spiders, Myriopods, and Peripatus, examined fresh objects in 0.75 

 per cent salt solution, to which is sometimes added weak acetic and 

 methyl-green acetic acid. The foregoing was only suitable for 

 young eggs, as older ones are too opaque. As a fixative, a cold con- 

 centrated sublimate solution proved the best. Water, 33 per cent 

 alcohol, and hot sublimate solution were not so useful. The cold 

 sublimate fixed in 5 to 10 minutes. The preparations were then thor- 

 oughly washed ; a few drops of tincture of iodine hastened the pro- 

 cess. Then 60 per cent spirit, and finally absolute alcohol. The 

 chorion is perforated with a fine needle, but the upper pole is to be 

 avoided. Ovaries are placed for several hours in chloroform, then 

 from one to three days (according to size) in paraffine at about 



* Ber. Naturf. Gesell. Freiburg, i. B. I. (1886); Journ. Roy. Micr. 



Soc., April, 1887. 



