MICROSCOPICAL JOURNAL: TRANSACTIONS OF THE ROYAL MICROSCOPICAL SOCIETY, AND RECORD OF HISTOLOGICAL RESEARCH AT HOME AND ABROAD. EDITED BY HENRY LAWSON, M.D., M.R.C.P., F.R.M.S., THE MONTHLY MICROSCOPICAL JOURNAL. JANUARY 1, 1874. I.-Notes on so-called Acarellus. By S. J. McINTIRE, F.R.M.S. (Read before the ROYAL MICROSCOPICAL SOCIETY, Nov. 5, 1873.) PLATE XLV. WHILST watching the habits of Poduræ and Pseudo-scorpions I have often been conscious of the presence in the cork cells of uninvited guests in the shape of acari of various species, either collected unintentionally by the camel-hair brush into the test tube together with the desired captures, or migrating from one cork cell to another of their own free will and pleasure. One of these has engaged a good deal of my attention. The first time I noticed it was in its character as a parasite upon a rather fine specimen of Obisium; six or seven of them clinging firmly to the legs and cephalothorax of the host, and remaining in the position they had taken up for days without causing any apparent inconvenience to the obisium. Indeed, at first I scarcely recognized them as parasites. Afterwards it was by no means uncommon in the locality which was my happy hunting ground (a back-yard with an apology for a garden at the rear of our house) to find under old bits of wood, brickbats, &c., Gamasi and Obisia, infested with these parasites, and once I caught a Gamasus with a perfect load of thirty or so of them on its back and legs, rendering it quite unrecognizable at first sight. By this time I had come to the conclusion that the earth in this particular place swarmed with this acarus, and it was no longer a novelty. I felt quite certain, moreover, that there were two species. On transferring the infested Obisia, &c., to my cells, I soon found that their little parasites occasionally left the host's back and wandered over the floor and sides of the cork cells; sometimes fixing themselves on the glass cover. Whilst in this position I availed myself of the opportunity of a closer inspection, and occasionally mounted them in balsam. Up to this point I had not been able to guess what they were, but now I obtained some scanty information. I saw that after they were mounted the two hinder pairs of legs were not so apparent as when the creature was alive. In most cases the position VOL. XI. B |