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VOL. XVIII. LONDON, JANUARY, 1886. No. i 



TWELVE YEARS' EXPERIENCE WITH RUBBER STOPPERS. 



USED IN THE BIOLOGICAL COLLECTION OF THE 



MUSEUM IN CAMBRIDGE. 



BY DR. H. A. HAGEN, CAMBRIDGE, MASS. 



The late Professor L. Agassiz, in 1867, requested of me a detailed 

 plan for the development of the entomological department of the Museum, 

 Among the different collections proposed was a biological collection simi- 

 lar to my own for Neuroptera and Pseudo-neuroptera, but extended to 

 include all Arthropoda. The Professor in a marginal note stated that this 

 collection should be commenced immediately, and developed as rapidly 

 as possible. In my collection the alcohoHc objects were included in vials 

 placed horizontally near the pinned dry objects, so that all belonging to 

 one species were together and presented a clear view to the observer. I 

 used vials closed with cork stoppers, which for a small collection and by 

 a continual supervision, proved sufficiently safe. Nevertheless experi- 

 ments were made with several substances, hoping to prevent the evapor- 

 ation of the alcohol and the necessity of refilling a large number of vials 

 every six months. This arrangement is, as stated, sufficient for a small 

 collection, but when applied upon a comprehensive and extended scale, 

 proves inadequate. The continual supervision and refilling of several 

 thousand vials would have needed a considerably larger expense and a 

 special assistant. The best velvety cork stoppers did not do as well here 

 as in Europe, owing to the greater changes of temperature. Experiments 

 were made during six years upon a large number of substances in the 

 hope of increasing the efficiency of the cork stoppers. Fats, tallow, 

 stearine to impregnate the cork, wax, sealing wax, different resins and 

 varnish, shell-lac, iron-lac, guttapercha and India rubber in different solu- 

 tions, thick oil paint, collodium, waterglass, very fine bladder around that 

 part of the cork placed in the vial, and glue and paste to cover the ex- 

 ternal part of the cork with strong paper and bladder, were subjected to 

 trial. Several of these substances were tried on an extensive scale and 



