i8 95 . NOTES AND COMMENTS. 229 



Formol as a Preserving Fluid. 



Every naturalist and every museum curator must necessarily be 

 interested in every new preserving fluid that is suggested. In the 

 January number of the American Naturalist, Mr. F. C. Kenyon describes 

 Professor T. Plum's employment of formol, the usual name of a 

 forty per cent, solution of formaldehyde in water. It is a clear 

 opalescent fluid with a sharp odour. It has the advantage of being 

 cheaper than alcohol, of having a more penetrating action, and, in 

 many cases, of preserving colours and microscopical details. Whole 

 mammals, reptiles, and fishes brought into a ten per cent, solution of 

 the fluid were hardened, and after three-quarters of a year were 

 entirely unchanged, although the fluid had never been changed. 

 They became very transparent, and the mucous matter, instead of 

 becoming stringy and opaque as with alcohol, remained quite trans- 

 parent. For histological work Mr. Kenyon recommends very strongly 

 a five per cent, solution of formaldehyde in fifty per cent, alcohol. 

 The tissues so treated showed no trace of shrinking, required a very 

 short time for hardening, and took the common histological stains very 

 readily. He makes the following general conclusion : — " In con- 

 clusion it may be said that for general purposes solutions of at least 

 more than two per cent, must be used in order to avoid the swelling 

 and de-colouration of specimens, and that from four to eight per cent, 

 will give the best result. For histological purposes formalin combined 

 with alcohol will give better results than either used alone." 



Do Adders Swallow their Young ? 



This perennial question has turned up again. It has been 

 raging in the Field for weeks, and the Saturday Review has a scholarly 

 article showing that in Spenser's time this curious maternal solicitude 

 was believed in. It is very unfortunate that, if the habit exist, no 

 adder which has swallowed its young has fallen into the hands of a 

 naturalist enterprising enough to hand over the specimen to a central 

 place of exhibition, like, for instance, the British Museum. Dr. 

 George Harley, F.R.S., seems to have made the nearest approach to 

 proving the supposed fact. Fishing in Scotland, he came on some 

 children in the state of horror and excitement familiar in all the tales. 

 If all countrymen know that the adder swallows its young, why are 

 they so invariably astonished when, in the narrations, they have come 

 upon an adder performing so harmless a feat ? But to return to Dr. 

 George Harley. Like a wise man, he impounded the adder, and 

 placed it in his fishing-basket. But with a perverse curiosity, he 

 opened the adder with a pocket-knife on his homeward road, and, 

 having satisfied himself that the young were inside, not in the 

 oviduct or in the stomach, but in an outgrowth from the lung, 

 apparently he had no more use for the adder. The specimen, no 



