378 SUMMARY OF CUERENT RESEARCHES RELATING TO 



Injecting Kidney of Teleostean Fish.*— J. Andige anaesthetised 

 the fish by putting chloroform into the water in which the animals were 

 contained ; the fish were then bled by means of a transverse cut made 

 through the body behind the abdominal cavity. When devoid of blood 

 the arterial system was injected by means of the following procedure. A 

 1 p.c. solution of nitrite of anryl in distilled water is syringed into the 

 caudal vein ; this done, the caudal vein is ligatured and the syringe in- 

 serted into the aortic orifice and the procedure repeated. The canula is 

 left in the artery, and through it is passed the injection mass. That 

 which gave the best results was gelatin coloured with Ranvier's soluble 

 blue ; Fol's metagelatin with Prussian blue was also successful. Injec- 

 tions of the venous system were made through the caudal vein or through 

 the posterior cardinal veins, after bleeding, and previously washing out 

 with nitrite of amyl solution. These venous injections were not in- 

 variably successful, and the author found that Retteser's procedure could 

 be relied on. This process consists in immersing the whole animal, with 

 the abdominal cavity freely open, in Midler's fluid. The vessels naturally 

 injected are distinguished with facility, and their dissection is quite easy. 

 Injections of the renal tubules were also tried by the methods of Guitel 

 and Altmann. Altmann's method, which consists in injecting olive oil 

 through the ureters and then treating the injected organ for 24 hours 

 with 1 p.c. osmic acid, gave the better results. Though rendering useful 

 service, neither was entirely satisfactory. 



Method of Preparing Frozen Sections of Brain-substance, f — 

 Y. Nageotte gives an instructive account of difficulties met with in such 

 work, and devices for overcoming them. He commences by cutting the 

 hemispheres into slices of about 1 cm. thick. The anterior and posterior 

 portions are cut vertically and the intermediate, horizontally, so that the 

 principal bundles are cut at right angles. The slices must be divided 

 into several portions suitable for the microtome plate. If a disc of 

 liver be first frozen on to the plate, and the block of brain frozen on 

 to this liver bed, the usual waste of the last portion of each block is 

 avoided. 



To avoid the deleterious effect of ice-crystals upon the grey matter, 

 the block is immersed first in 3 p.c. formalin. It is then sprayed with 

 methyl chloride on all its sides, and thus the surface is rapidly frozen. 

 It is then gummed to the microtome plate. This can be maintained at 

 a temperature of - 10° C. The sections are carefully removed with fingers 

 or forceps, and washed in water. Sections can be cut at a thickness of 

 40-80 /*. 



Before staining, the sections are placed in 90 p.c. alcohol for a few 

 minutes. The addition of 30 p.c. glacial acetic acid to this bath prevents 

 shrivelling. The section is then spread on a glass plate, and stained with 

 hamialum (Mayer's ha3inalum 2 parts, absolute alcohol 1 part) for half 

 an hour in a warm stove. It is then washed with water and placed in a 

 modification of Weigert's decolorising fluid, washed, passed through 

 alcohols, cleared in xylol, and mounted in balsam. 



* Arch. Zool. Exp6r. et G6n., xliv.(1910) pp. 275-624 (104 figs.). 

 t C.R. Soc. Biol. Paris, lxvii. (1909) pp. 542-5. 



