92 The Microscope. 



reduce many so-called mineral species to the rank of accidental, 

 though still highly interesting, varieties. But of still greater 

 importance is the recognition of the fact that the investigation by 

 the aid of the microscope of the processes by which minerals have 

 acquired their several characters, and the consequent tracing of the 

 evolution of mineral species and varieties, is calculated to raise min- 

 eralogy from its present rank as a merely classificatoiy science; to 

 infuse it with new life; to open out to it new realms of research, and 

 to invest it with a higher importance than is at present accorded to 

 it in the family of science. — Journal B. M. Society. 



Orienting Large Objects in Parapfine. — In embedding smaller 

 objects the orientation is facilitated by employing some such instru- 

 ment as Zeiss' dissecting microscope, but for larger objects a simpler 

 contrivance answers every purpose. The glass plate upon which the 

 embedding is to be performed is placed on top of an ordinary glass 

 dish, 5^^ deep and 10^=" in diameter is a convenient size, at the bot- 

 tom of which a small mirror is so adjusted as to make an angle of a 

 little less than 45^ with the horizon. With the mirror turned to- 

 ward the window, light traversing the sides of the dish is reflected 

 upwards, and renders the outlines of the object sufficiently distinct 

 for most purposes of orientation. — American Naturalist. 



NEWS AND NOTES. 



Professor Windle has announced to the British Association, as 

 conclusions from his researches on the subject, that man's original 

 dentition included six incisors in either jaw; that two from each 

 jaw have gradually disappeared; that this loss is due to the contrac- 

 tion of the anterior part of the palate; that this process of contraction 

 will probably go on and result in the loss of two further incisors: 

 and that the conical shape of many of the supernumerary teeth indi- 

 cates a reversion to the primitive type of tooth.— Medical Neics. 



In his paper on the Chromatology of Certain Actinas (Philos. 

 Trans., vol. 176), MacMunn states of the " yellow cells," that the 

 fact that they appear to cause a supi3ression of those pigments which, 

 m other actineae, appear to discharge a respiratory function, is an 

 argument in favor of their being regarded as symbiotic algae. 



Wolf has found in the inter muscular connective tissue of the 

 flesh of oxen a parasite which is apparently the form of an ascaris. 

 It is encysted like trichince, but is somewhat larger, and is nearly 



