

CUTTING Wl> COUNTING SECTIONS. 311 



changing its shape. He then allows the reagenl to act upon the 

 brain, carefully isolated, until ii assun j tint. It is 



then Boaked several hours in distilled water, but ma\ be fixed by 

 treating it su< ly with alcohol dilut< d one third, alcohol at To . 



and alcohol at 90°. I were thus obtained enly im] 



oated throughout their entire mass « itli osmium. 

 In 1 1 1 € . — i cases h«- colored the nuclei by placing the piece some 



hours in (aniline and alum decidedly acidulated with acetic acid. 



On being taken OUt of this Stain and washed, tin- brain is dehydra- 

 ted, embedded in paraffin e, and cut into section- .' , nun. in thick- 

 D( —. and mounted serially. Besides frontal, lateral, and sagittal, 

 oblique sections were made. 



- nor 6. < uccato, in preparing the brain of OrthOptera, snips off 



the head of the insect with a pair of scissors, and pins it on cork. 

 Thus fixed, the head is immersed in 0.75 per cent Natl solution. 

 Then, with the aid < I rs ami forceps, the chitinous sheath and 



the eyes are removed from the supra-cesopuageal ganglion, and the 

 specimen removed i" a watch-glass full of .-alt solution, wherein the 

 trachea' and muscle- are removed. After a short time the object is 

 placed for forty-eight hour- in Flemming's mixture, and then, ha\ ing 

 hern w.ii washed, the resl of the muscle- and the fat are removed 

 from the ganglion. It is mxt put in :>ti per cent spirit, ami gradu- 

 ally hardened. A.fter dehydration it is embedded in paraffine. The 

 sections were fixed down by Mayer's method, ami stained with a 

 saturated watery solution of acid fuchsin. The fixative used was 

 Rabl's solution (chromo-formic acid and platinum chloi 

 i.Iourn Roj Mi. r. Boc . Dec. 1887, p. 1045.) 



Preparing the Sympathetic Nervous System of the Cockroach — l»r. 

 M. Hostler pursued the following mode in examining that of Peri- 

 planeta orientaUs: — The fresh part- of the insect to be examined were 

 held pver osmic acid for two or three minute-, washed, and trans- 

 ferred to weak alcohol. They were then stained with picro-carmine 

 for twenty-four hour- b, aeath the bell-jar of an air-pump, ami were 



found to lii> perfectly hardened. When all traces of alcohol had 

 been removed by washing they were placed in filtered white of 

 At the end of about two hours the albumen was 

 by weak and then by absolute alcohol, wanned :. I C, SO a- l" 



bring about a- even a coagulation a- possible. Th< I can then 



be treated in the usual way with oil of cloves, i mb< dded in paraffine, 

 and cut with a microtome, (/cits, fur Wissen. Kxxix. 



I, 572; also Journ.Roy. Micr. Soc, i v -" 

 Making Sections through and Bleaching the Eyes of Insects. — 1>: 3 

 .1. Bickson's method i- as follows: "For m g sections tlu 

 the ey< of M tea tomHoria 1 have found it best to dissect away the 



