ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 501 



Abbott, C. A. — An improvement in the method of preparing Blood Serum for use in 

 Bacteriology. Med. News, 1887, pp. 207-8. 



Bolton, M. — A Method of preparing Potatoes for Bacterial Cultures. 



Med. News, 1887, p. 318. 

 LocKWOOD, S. — ^Raising Diatoms in the Lahoratory. 



Journ. New York Micr. Soc, XL (1886) pp. 153-66 (2 pis.) 



(S) Preparing- Objects. 



Notes on the Technique of Emhryology.* — Dr. H. Henking finds 

 that the eggs of Phalangida can be kept through the winter without getting 

 covered with fungi, and so damaged or even destroyed, by placing them in 

 an ordinary oven on sand or earth kept moistened with distilled water. 

 The usual antimycotics, such as carbolic and salicylic acid and alcohol, are 

 quite unreliable. 



Ova are best preserved with boiling water and chrome-osmium-acetio 

 acid, and Perenyi's fluid is also useful, but sublimate, chromic acid, picro- 

 sulphuric acid, 20 per cent, nitric acid are less reliable. Eggs of 

 Phalangida being little penetrable by reagents, it is almost indifferent 

 whether boiling water or a boiling 1/2 per cent, solution of chromic acid bo 

 used for hardening. 



Owing to the difficulty of staining eggs the author prefers to rupture 

 the shell. This is done by means of two very sharp needles under a 

 power of 40 or 50 diameters and in 70 per cent, spirit. The eggs are 

 previously hardened in 90 per cent, alcohol, and when transferred to the 

 weaker spirit are easily lacerated without damage to their contents. The 

 outer casing only of the shell is broken ; this, the more brittle, is covered 

 with a uterine secretion to which foreign bodies are frequently attached, so 

 that there is an extra advantage in removing it. The more flaccid inner 

 shell serves to protect the egg contents. 



The eggs are stained in toto best with Grenacher's borax-carmine or 

 with eosin-hsematoxylin, or with Hamann's neutral acetic carmine. If 

 eosin-haematoxylin be used, the eggs are washed with a weak alum solution 

 and then transferred to alcohol which is faintly stained with eosin in order 

 to prevent loss of colour. Ova treated with borax-carmine are overstained 

 and then decolorized in slightly acidulated 70 per cent, spirit. 



After having been stained and dehydrated the eggs are transferred to 

 a mixture of equal parts of bergamot oil and alcohol for some hours, then 

 to pure bergamot oil, and from this to a mixture of bergamot oil and 

 paraffin. They are next saturated in paraffin at a temperature of 55° C, 

 and when ready are fished out with a spoon and allowed to drop into a 

 vessel filled with cold water in order to cool the paraffin rapidly. 



Orientation of the ovum is most easily effected by means of a glass ring 

 2 mm. high. This is placed on a slide and filled with melted paraffin, in 

 which the eggs are immersed. The slide is then placed under a dissecting 

 Microscope with a power of 40 or 50 diameters, and the egg moved into 

 the desired position by means of a needle heated in a spirit-lamp. Though 

 manual dexterity is required for this operation, it is more simple and 

 easier than to employ the apparatus devised for this purpose. The paraffin 

 block when cool is easily removed from the ring, and is then melted on 

 to a cork. 



The treatment of brittle sections, more especially in the case of 

 Arthropoda, is always difficult. The usual methods for obviating the 

 tendency to crumbling are to brush the section surface over immediately 

 before cutting with collodion or with collodion thinned down with ether. 



* Zeitschr. f. Wiss. Mikr., iii. (1886) pp. 470-9. 



