224 Analyses of Books. 



When examined under the microscope they were found to 

 be round tubes ; they are more or less translucent, and 

 their colour by transmitted light is brownish yellow. These 

 tubes have round apertures on their sides, whose margins 

 are thicker than the rest of the sides ; some of them when 

 of a large size, however, have no edges of any considerable 

 diameter. When heated to whiteness in platinum foil 

 before the blowpipe, these tubes lost their translucency 

 and became very brittle. The diameter of these tubes was 

 from about -00049 inch to -0000908 inch. There is a remark- 

 able appearance observed when the miscroscope is directed 

 through one of the apertures upon a distant (entfernten) 

 object. This object appears double. One of the figures 

 stands upright about -0004 behind the opening; it is, at 

 least so distinct, that we can see the window-post clearly. 

 The second figure is inverted, and appears before the open- 

 ing ; it is more indistinct than the first. These appearances 

 belong to the phenomena of diffraction. The form which 

 the charcoal assumed, by the powerful heat applied in the 

 manner described, is similar to the filamentous matter ex- 

 amined by Dr. H. Colquhoun, which was obtained during 

 some trials made by Mr. Macintosh to convert iron into 

 steel, by surrounding it with coal gas in an air tight iron 

 chest.* 



Article VIII. 



Analyses of Books. 



I. — Philosophical Transactions of the Royal Society of London 

 for 1835, Part II. 



{Concluded from page 149.) 



ANATOMY AND PHYSIOLOGY. 



Continuation of the paper on the relations between the nerves of 

 woolton and of sensation, and the brain ; more particularly, on 

 the structure of the medulla oblongata and the spinal marrow. 

 By Sir Charles Bell, F. R. S., &c. 



The investigations detailed in this paper refer to the structure of the 

 spinal marrow, and its relations to the encephalon on the one hand, 

 and to the origin of the nerves on the other. If, after having laid 

 bare the medullary columns of the spinal marrow, we split up the 



* Poo-o-eiidorff's Ann. xxxv. 468. — Thomson's Inorganic Chemistry, i. 160, 



