128 SUMMARY OF CURRENT RESEARCHES RELATINQ TO 



mounts. Imagine a slip of ground glass with a transparent spot m. 

 the centre, upon which objects can be mounted, and one can thus 

 form an idea of the appearance of these slides." 



Spring Clip Board.*— Mr. W. Stringfield gives the accompanying 

 sketch (Fig. 26) of the spring clip boards he has had in use for some 

 time, and which, for reducing the breakage of thin glass covers to a 

 minimum, economy of construction, and convenience of moving, far 



Fig. 26. 



surpass, he considers, any arrangement that has come under his notice. 

 They are made of mahogany, but of course pine or other wood can be 

 used. All, however, should be baked previously to finally planing up. 

 A is a piece of mahogany 12 X 7| X f inches; B two strips, 

 each securely fastened down the centre of the base board A by 

 eleven screws; CC pieces of watch or crinoline steel, 3| inches 

 long, ^ inch wide, with a hole punched in either end to allow of a 

 small brass pin passing through for securing the pressors ; D D small 

 pieces of phial corks ; E E E E four screws fitting in corresponding 

 holes drilled in the bottom of each board, thus allowing a number to 

 be placed one on the other without injury to the slides, and admitting 

 a free current of air. 



Examination of Living Cartilage.f — J- M. Prudden found the 

 episternum of the frog, especially of Mana temporaria, an extremely 

 good object in which to examine cartilage in the living animal. A 

 moderately curarized frog should be taken, and an incision made in 

 the skin from the lower jaw to the middle of the sternum, and then 

 two cross cuts ; the operator must turn back the edges of the skin, 

 and divide the submaxillary muscle, thus exposed, near the middle, 

 avoiding the large veins which pass inwards over the apex of the 

 episternum. The latter lies at the bottom of the incision, being 

 covered only by a somewhat loose connective tissue. If the delicate 

 lamina of connective tissue between the episternum and hyoid bone 

 are now cut through, and the head turned back at right angles to the 

 body, the episternum is extruded from the wound, projects forwards, 



* Sci.-Gossip, 1881, p. 232 (1 fig.) 



t Virchow's Archiv, Ixxv. pp. 185-98. Cf. Jahresber. Anat. u. Physiol,, 

 viii. pp. 11-12. 



