538 SUMMARY OF CURRENT RESEAT^CHES RELATING TO 



alcohol, ami places them for fifteen to twcuty minutes in a mixture of 

 equal parts of the following solutions: — (o) Carmine, 2 ; borax, 8; 

 water, 130. (h) Indigo-carmine, 8 ; borax, 8 ; water, 130, They aro 

 then treated with a saturated solution of oxalic acid, washed, and 

 mounted in balsam. 



The ground-substance of the unchanged cartilage is not stained, 

 while at the margin of ossification it is pale red ; the cartilage cells 

 arc reddish, with dark nuclei ; bone and osteoclasts, red ; blood-cor- 

 puscles, green. The latter stain is a specific property of haemoglobin, 

 and, of other tissues, only the inner root-shcath of hairs U cs on a 

 greenish hue. 



Preparing the Sympathetic Nervous System of Periplaneta 

 orientalis.* — Dr. M, Koestler recommends the following process : — 



i he fresh parts of the animal to be examined are held over osmic 

 acid for two to three minutes, washed, and transferred to weak alcohol. 

 They are then stained with picro-carmine for twenty-four hours beneath 

 the bell-jar of an air-pump, and aro found to be perfectly hardened. 

 \^ hen all traces of alcohol have been removed by washing they aro 

 placed in white of egg, freed by filtration from all fibres, &c. 



At the end of about two hours the albumen is coagulated, first by 

 weak and then by absolute alcohol, warmed to 40° C, so as to bring 

 about as even a coagulation as possible. The object can then bo 

 treated in the usual way with oil of cloves, imbedded in paraffin, and 

 cut with a microtome. 



Fixing, Staining, and Preserving Infusoria.f— For fixing In- 

 fusoria, Dr. L. Cattaneo employs a watery solution of chloride of 

 palladium, which hardens the organism in a few minutes without 

 modifying its form or blackening it, and allows the granules and cell- 

 nuclei to stand out prominently. Similar effects are produced by 

 double chloride of gold and cadmium, which brings out the cell-nuclei 

 much better than the former. For tlie study of protoplasmic networks 

 iodide of mercury and potash (1-2 per cent.) is of use, as it stains 

 the granules of the proto^dasm black, and brings out clearly the 

 granules of the cell-nuclei. Beautiful preparations can be made with 

 corrosive sublimate, in 5 per cent, solution, which kills the infusorian 

 instantly, and rapidly fixes all the anatomical elements. Fm-ther, it 

 gives such consistence to the protoplasm that the most complex staining 

 processes can be carried out. 



Specimens treated with osmic acid are dark, and lose their 

 transparency. 



Cattaneo places in the second rank as fixing media chromic, picric, 

 and picro-sulphuric acids, and bichromate of potash. 



Preparations can be with advantage treated with nitrate of silver 

 (1/2-1 per cent, solution), and afterwards washed with a solution of 

 acid sulphate of soda. As staining reagents, magenta-red and fuchsin 

 give good, and nigrosin and logwood still better results. Both 



* Zeitschr. f. Wiss. Zool., xxxix. (18S3) pp. 572-95. 

 t Bollelino Scientifico, 1883, Nos. 3 and 4. 



