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 similar 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 alcoholic 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 experiments were made with several substances, hoping to prevent the evaporation of the alcohol and the necessity of refilling a large number of vials every six months.