1898.] MICROSCOPICAL JOURNAL. 73 



weeks, the earthly matter of the bones will all dissolve 

 out and leave the cartilage. The color is reduced and 

 the thickness diminished, but the arteries and their 

 blood are so little altered that when mounted the aorta 

 and branches are well seen over the whole animal. 



Keeping. ^ — When the dried animals have been pre- 

 pared and it is not desired to mount them at once in 

 Canada balsam, they may be kept in tin boxes with 

 flannel which has been thoroughly dried just before use. 

 The specimens wil) keep for many months before mould 

 appears. 



Final Mounting. — At the four corners of the glass 

 gum small pieces of blackened card board of such thick- 

 ness that the cover glass will just clear the object. 

 Keep the glass with the animal for a time in benzole 

 meantime warming the cover-glass on a suitable 

 stand over a small burner and fair quantity of liquid 

 balsam placed in the centre. Take the glass and animal 

 out of the benzole and carefully place over the balsam so 

 as to catch up as few bubbles as possible. The benzole 

 will cause the greater part to bust and disappear. If 

 there is too little balsam, more may easily be run in 

 between the glasses and if there were but few bubbles 

 they will soon go. If too many, slightly incline the slide 

 till they rise to one edge and then remove them. 

 If kept cold for a few days the balsam will harden the 

 edges. Then bind round with thin paper of best quality 

 made thoroughly wet with gum. When dry, the con- 

 traction may squeeze out some superfluous balsam. 

 This paper should then be varnished and finally strips of 

 good black paper may be glued well round the whole. 

 Use all possible care to enclose the balsam tlioroughly so 

 as to avoid its turning yellow and to prevent leakage 

 when the slide has been heated by the lantern or other- 

 wise. The slides are kept preferably in the dark to 

 prevent possible fading. — H. C. Sorby in Nature. 



