The Microscope. 311 



ing sizes, filling up, apparently the meshes of connective fibrous 

 tissue, which is quite thick, fibrous, homogeneous, polarizes light, 

 and is probably cellulose or woolly fibre, very resistant to outside 

 influences. 



Physical Properties of the Axis Cylinder. — Mr. Franz Tangl, 

 after investigating the histology of crushed peripheral nerves, 

 {Archiv. f. niikr. Anatoniie, 1887, page 4l)4.) reaches some interest- 

 ing conclusions regarding the axis cylinder. The preparations were 

 made after Neumann's method of applying a temporary ligature to 

 the nervus isiadicus of a guinea-pig. The portions were then 

 removed and hardened in Miiller's fluid and afterwards stained in a 

 1^ aqueous solution of nigrosin, or an alcohol-aqueous solution of 

 fuchsiu. Tangl found sach pi'eparations far better for axis-cylinder 

 studies than those prepared in the usual way with osmic acid, which 

 blackens the medullary substance, thus obscuring the cylinder. 



Studying these preparations he found, (1) that when the liga- 

 ture had been tightly drawn, the axis cylinder was usually severed 

 and that the two poi-tions did not, as claimed by Neumann, mix with 

 the surrounding substance, but drew away, curled up and remained 

 as distinct bands. (2) That when the ligature had been more lightly 

 applied the axis cylinder was not severed, but only compressed, 

 though the sheath and medullary substance were broken. From this 

 he concludes that the axis cylinder is a soft, firmly knit, (therefore 

 not fluid,) and, pei'haps, elastic, constituent of the nerve fibre. His 

 studies are still in progress at the biological laboratory in Biida-Pest. 



Blood of Smerinthus tili^ Pupa. — At a meeting of the Ento- 

 mological Society of London, on December 1st, Mr. Poulton 

 exhibited the bright green blood of the pupa of Smerinthus tilice, 

 which is one of many lepidopterous pupse possessing a chlorophyll - 

 like pigment (called metachlorophyll by Mr. Poulton) in the blood. 

 By means of a micro- spectroscope the most characteristic absorption- 

 band of the pigment, together with its resemblance to chlorophyll, 

 was shown. — Am. Naturalist. 



Eyes of Protozoa. — So-called eyes have often been described in 

 the Protozoa. The latest instance is that of Gymnodinium polyphe- 

 inus, described by Pouchet at a recent meeting of the French 

 Academy. In this species of Flagellate there is described a strongly- 



