GUTTING AND MOUNTING SECTIONS. 311 



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

 brain, carefully isolated, until it assumes a deep gray tint. It is 

 then soaked several hours in distilled water, but may be fixed by 

 treating it successively with alcohol diluted one third, alcohol at 70, 

 and alcohol at 90. Pieces were thus obtained very evenly impreg- 

 nated throughout their entire mass with osmium. 



In most cases he colored the nuclei by placing the piece some 

 hours in carmine and alum decidedly acidulated with acetic acid. 



On being taken out of this stain and washed, the brain is dehydra- 

 ted, embedded in paraffine, and cut into sections ^ v mm. in thick- 

 ness, and mounted serially. Besides frontal, lateral, and sagittal, 

 oblique sections were made. 



Signor G. Cuccato, 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 NaCl solution. 

 Then, with the aid of scissors and forceps, the chitinous sheath and 

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

 specimen removed to a watch-glass full of salt solution, wherein the 

 tracheae and muscles are removed. After a short time the object is 

 placed for forty-eight hours in Flemming's mixture, and then, having 

 been well washed, the rest of the muscles and the fat are removed 

 from the ganglion. It is next put in 36 per cent spirit, and gradu- 

 ally hardened. After dehydration it is embedded in paraffine. The 

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

 saturated watery solution of acid fuchsin. The fixative used was 

 Rabl's solution (chronic-formic acid and platinum chloride). 

 (Journ. Roy. Micr. Soc., Dec. 1887, p. 1045.) 



Preparing the Sympathetic Nervous System of the Cockroach. Dr. 

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

 planeta arientalis: The fresh parts of the insect to be examined were 

 held over osmic acid for two or three minutes, washed, and trans- 

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

 for twenty-four hours beneath the bell-jar of an air-pump, and were 

 found to be perfectly hardened. When all traces of alcohol had 

 been removed by washing they were placed in filtered white of egg. 

 At the end of about two hours the albumen was 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 

 be treated in the usual way with oil of cloves, embedded in paraffine, 

 and cut with a microtome. (Zeits. fur Wissen. Zoologie, xxxix. 

 1883, 572; also Journ.Roy. Micr. Soc., 1885, 538.) 



Making Sections through and Bleaching the Eyes of Insects. Dr. S. 

 J. Hickson's method is as follows: " For making sections through 

 the eye of Musca vomitoria I have found it best to dissect away the 



