[185] 



Selcctcb IRotee from tbe Societ?'6 



1Rote^Booft0* 



staining. — I think there can be no doubt that staining adds to 

 the value of a shde. It differentiates the component parts of 

 tissues, and enables the elements to be recognised with much more 

 facility. Not that an educated eye cannot distinguish them 

 without staining, but I find from experience that in demonstrating 

 histological specimens to men who see the structure for the first 

 time, it is useless to show unstained ones. I have used chiefly 

 hsematoxylin and carmine fluids. Carmine does not as a rule 

 stain so evenly as hsematoxyHn, and it takes a much longer time, 

 which is an objection with delicate sections, and, moreover, there 

 is such a glare caused by it — especially when working at night — 

 that the object becomes more or less hazy, thus counteracting to 

 some extent the value of the staining. The fluid which I always 

 use, and which I strongly recommend, is as follows : — Extract of 

 HaematoxyHn, i drachm (60 gr.); Alum, 3 drachms (180 gr.). To 

 be well rubbed together in a mortar, and then 5 drachms of water 

 added by degrees whilst still triturating. Filter, and to the filtrate 

 add Rectified Spirit, J drachm. For use, three or four drops of 

 this fluid should be added to two drachms of water in a watch- 

 glass, and the mixture carefully filtered, as some precipitation 



occurs. E. C. BOUSFIELD. 



Spine of Dog-Fish.— The "spine" (scale) of dog-fish, like that 

 of other placoid fishes, shows an approach to tooth-structure ; the 

 dentinal tubules are stouter and more branched, and less parallel 

 than those of the mammalian tooth, though closely resembling 

 those of the teeth of some fishes. The enamel seems absent. 



H. F. Parsons. 



Shell of a Brachiopod. — Brachiopods differ from ordinary 

 bivalves, in that the valves are front and back, instead of right and 

 left. The ventral valve is prolonged in many species into a perfo- 

 rated beak, like that of an ancient Roman lamp ; hence, they are 

 called "lamp shells." There are also internal anatomical differ- 

 ences so great, that by some modern zoologists the Brachiopods 

 are removed altogether from the Mollusca. The existing Brachio- 

 pods are the few lingering remnants of a once numerous family. 

 If nobility be measured, as some people measure it, by length of 



