CORRESPONDENCE. 



The Mounting of Wet Preparations for Museums. 



In his interesting paper, " Morphology at the National Museum," recently pub- 

 lished in your pages, Mr. Ridewood alludes to a difficulty experienced in labelling 

 dissections intended to be preserved in spirit. 



Such a difficulty I also encountered when recently mounting some preparations 

 for the Index Collection of Invertebrates, now in course of formation at Leicester, 

 and, not feeling satisfied with the methods in vogue, either at the National Museum 

 or at Oxford, I finally adopted the expedient of substituting thin silver wire, coated 

 with vermi'ion, for the usual paper pointers. 



The oil colour should be used (mixed with a little medium to facilitate drying) 

 and applied to the wire while the latter is rigidly extended. In attaching a pointer 

 to its label, one of the extremities is bent at right angles and passed through a per- 

 foration in a thin strip of paper which is fastened to the back of the label with 

 coaguline. The bent head of the pointer is thus firmly held between the two pieces 

 of paper, leaving the rest of the wire projecting behind. When labelling, the 

 pointer may either be thrust into the tissue, or, where this cannot be done, the 

 judicious use of a few drops of photoxylin will suffice to hold the label in any desired 

 position. 



This method is specially useful when dealing with specimens which project con- 

 siderably beyond the glass plate to which they are affixed, since the labels can be 

 brought to a level with the surface of the preparation. When the object is a flat 

 one {e.g., the nerve-chain oi Astacjis), I prefer to attach the labels to the glass plate with 

 coaguline. In this case, one extremity of the pointer rests on the tissue, the other is 

 held between the label and the glass. 



The advantages of such a pointer seem to me to be twofold ; first, its rigidity, 

 and consequent power of supporting the label in any position, and, secondly, its 

 uniform thickness, having in this respect an advantage over paper. I may mention 

 that, when the wire has been properly coated, I have not detected any perceptible 

 change in colour after an immersion of some months. However, should contact 

 with the metal tend in time to produce deterioration in this respect, it would not be 

 difficult, I imagine, to substitute a rigid, non-metallic substance for the wire here 

 recommended. 



I note that Mr. Ridewood urges the transparency of paper when immersed in 

 spirit as a reason for attaching the labels to the outside of the preparation jar. I 

 do not myself think that this transparency interferes to any serious extent with the 

 legibility of the print, added to which greater uniformity in appearance is secured, 

 to say nothing of the facilities offered for indicating the various parts of the dissec- 

 tion by direct contact with the extremity of the pointer ; to my mind a point of no 

 little importance. 



Leicester Museum. F. R. Rowley. 



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