478 AXIS-CYLINDER AND DENDRITE STAINS. 



906. RAMON Y CAJAL'S Diffusion Process (Rev. Trim. Micr., i, 

 1896, p. 123).- -The brain is exposed, and by means of a sharp razor 

 the cortex is divided into slices about 2 mm. thick. The slices 

 are then covered on both sides, either with finely powdered methylene 

 blue or impregnated with a saturated solution of the same and 

 replaced in their natural situation. The brain is covered over again 

 with its case for about half an hour, after which the slices are removed 

 and fixed for a couple of hours in Bethe's ammonium molybdate 

 solution. They are then washed and hardened for three or four 

 hours in a mixture of 5 parts of chloroplatinic acid, 40 parts of 

 formalin, and 60 parts of distilled water. After another quick wash 

 and a brief treatment (? a- few minutes) with a 1 : 300 alcoholic 

 solution of chloroplatinic acid, they are dehydrated and embedded 

 in paraffin. The sections may also be quickly treated with the 

 same weak alcoholic solution of chloro-platinic acid, cleared with 

 xylol or bergamot oil, and mounted in the usual way. 



907. CATOIS' Method for Fishes (C. R. Ac. Sc., cxxiv, 1897, p. 204). 

 -Small quantities (2 to 3 c.c.) of a concentrated solution of 



methylene blue, prepared with physiological salt solution, is injected 

 into the branchial vessels or intramuscularly. The brain is removed 

 after half an hour, divided into slices, and then left for another 

 half an hour in the same concentrated solution used for injecting 

 the animal. The slices are then fixed in the usual ammonium 

 molybdate solution, or in Cajal's chloroplatinic acid mixture. 



908. See also the valuable account of DOGIEL Methylen-blau zur 

 Nervenfdrbung in the Enzykl. mikr. Techn., 2nd ed., 1910, and the article 

 of GORDON in Anat. Rec., iv, 1910, p. 267 ; and that of MICHAILOW in 

 Ztschr. wiss. Mikr., xxvii, 1910, p. 1, in which the literature of the 

 subject is critically discussed. 



