and Laboratory Methods. 2021 



r-4«i D H D u u 1.U- . , • As fixing agents the author used 95 per 



Catols, E. H. Recherches sur 1 Histologic et ° ° ^ 



I'Anatomie Microscopique de I'Encephale cent, alcohol, 10 per cent, formol, Flem- 



chez les Poissons ^''"•/''V "^^ ^^ ^'■^"" king's chrom-osmic-acetic, Mayer's pi- 

 et de la Belg. 36 : 1-166, pis. i-x., 1901, ° ' / r 



cro-nitric and Perenyi's chromo-nitric, 



and especially recommends the last as excellent for nervous tissues. The stains 

 used were Delafield's and Ehrlich's haematoxylins and various anilins, thionin 

 being most highly recommended. Dogiel's method of using methylen blue was 

 discarded after several unsatisfactory trials in favor of the following procedure : 

 A concentrated solution of methylen blue (Ehrlich of Griibler) in normal salt 

 solution was injected in the branchial vessels or in the dorso-lateral muscle 

 masses. One or two cubic centimeters of this solution produces immediate 

 intoxication, and at the end of a half-hour one finds the nerve centers more or 

 less impregnated with the stain. The brain is then carefully removed and cut 

 in four or five pieces in the sagittal or frontal plane. It is then placed for an- 

 other half-hour in a saturated solution of the methylen blue and subsequently 

 treated by the molybdate of ammonia method of Bethe or by the forrnol or plat- 

 inic chloride method. The methylen blue method thus employed gave good results 

 for the fibrillar zones of the optic lobes, the nerve facicles and commissural 

 fibers and the nuclei and radical fibers of the cranial nerves. 



The Golgi method was used with good results, especially upon young ani- 

 mals. It is relatively easy to impregnate the following regions : the anterior and 

 inferior lobes and at times the optic lobes and the superficial zones of the cere- 

 bellum. It is more difficult in the case of the olfactory bulb, the thalamenceph- 

 alon, geniculate body, round nucleus, habenula, cerebellar peduncles, and deeper 

 layers of cerebellum and cord. When the brain exceeded four millimeters in 

 length it was cut in sections before immersing in the fixing fluid. After numer- 

 ous trials the amount of osmic acid in the first bath was reduced below the 

 customary proportion, the following solution being used : 



3 per cent, bichromate of potash, - 6 parts 



1 per cent, osmic acid, - ... 1 part 



The duration of the first bath was 24-48 hours, and of the second (.75 per 

 cent, silver nitrate) 36-48 hours. The Cox-Golgi method was also used with 

 profit. c. A. K. 



T-> ^- u/ I /->u .• u o The larva of the Chrysomelid beetle, 



lower, W. L. Observations on the Structure •' 



of the Exuvial Glands and the Formation Leptmotarsa decem-lmeata, was employed 



of the Exuvial Fluid in Insects. Zool. -^^ ^^^5 ^^^^ -p^g method used will be 



Anz. Z5 : 466-472, 8 figs., 1902. _ ■' 



useful in other cases where cuticular 



structures interfere with rapid penetration of fixing fluids and prompt fixation of 



tissues. Living larvae were placed for a minute or less in : 



Saturated corrosive sublimate in 35 per cent, alcohol, 70 cm.^ 

 Glacial acetic acid, -.-... l cm.^ 



This was heated to temperature of 60°-65°C. and the larvae were quickly 

 removed, cut in several pieces and placed in a weaker mixture : 



Saturated corrosive sublimate in 35 per cent, alcohol, 99 cm.^ 

 Glacial acetic acid ------ l cm.^ 



The larvae were allowed to lie in the fluid for thirty minutes to six hours, 

 according to their size. A mixture of cedar-oil and xylol was used for clearing. 

 Heidenhain's iron haematoxylin and Mayer's haemalum followed by orange G or 

 Zwaardemaker's safranin were used as stains. Material killed in Hermann's, 

 Flemming's and von Rath's mixtures give good results, but less uniformly than 

 the acetic-sublimate. Perenyi and the various picric acid mixtures were entirely 

 unreliable and hot water only gave fair results. c. a. k. 



