BIOLOGICAL AND MICROSCOPICAL DEPARTMENT. 3 



in the text-book on physiology, but with the description reversed? 

 and therefore correct. The corpuscle is, however, described as in 

 focus when the periphery' is in focus. Of the other text-books 

 now within our reach, Dalton has it correcth' on page 214 of his 

 third edition ; Flint, Kirke, Ranke in his " Grundziige der Physio- 

 losfie," and Strieker in his "Handbuch der Lehre von den Gewe- 

 ben," refer to the reversal of light and shadow, but do not state 

 the circumstances under which it takes place. Marshall makes 

 no allusion to it. 



Dr. McQ,uillen exhibited five microscopical specimens pre- 

 pared by Dr. George D. Harrlman, of Boston, consisting of 

 dentine, cementum, and bone, which had been acted upon by 

 dilute muriatic acid removing the earthy salts and leaving the 

 cartilaginous ba^s of which those structures are composed, the 

 latter of which had then been stained with carmine. These speci- 

 mens had been prepared with a view of demonstrating that dentine 

 does not consist of tubular and intertubular structures; also that 

 in cementum and bone the lacunae and canaliculi are not empty 

 spaces, but occupied by a soft solid body or substance. 



Fiff. 1. 



February 6. 

 Director S. W. Mitchell in the chair. 



Sixteen members present. 



Mr. William H. Walmslej^ exhibited slides showing the differ- 

 ence between the torn edge of our ordinar3^ paper and that of the 

 thick, strong paper used by the Chinese for the manufacture of 

 clothing. Both appeared to be composed of cotton, but the foreign 

 article bore the aspect of being made directl}^ 

 from the cotton fibres, instead of from com- 

 minuted woven fabrics. 



Dr. McQuillen directed attention to a re- 

 markable specimen of hypertrophy of the roots 

 of a left superior molar measuring 2^ inches 

 in length by 2f inches in circumference, and 

 weighing 12^ dwts. (Fig. 1), which he had ex- 

 hibited at a previous meeting and of which he 

 had promised to make a microscopical ex- 

 amination. This he had done, and now sub- 



