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Show ON REGENERATION OF THE TAILS OF MICE. 491 a corresponding way. The dorsal (supra-intestinal) blood-vessel could be distinctly seen through the body-wall, and it branched in the same fashion as the body. Each branch bore its own four rows of setae. Mr. H. B. Fantham, B.Sc., F.Z.S., exhibited and made the following remarks upon microscopic preparations of a new Haemosporidian parasite belonging to the genus Piroplasma, from the blood of the white rat:-The parasite is endoglobular and the trophozoites are ovoid (05 to T5 /j, in diameter) or pear shaped (2 to 3 /j, long and 1 to 1 ‘5 /u broad), and usually uninucleate. A single pear-shaped trophozoite 'often occurs alone in a blood-corpuscle of the host. Some amoeboid forms were seen in the spleen. Schizogony takes place inside the red blood-corpuscles by simple fission. Double infection of a blood-corpuscle may occur, while free ovoid forms of the parasite have also been seen. For this new species of Piroplasma in the white rat, the name Piroplasma muris is proposed. The parasites are not numerous in the peripheral circulation of the host, but occur in greater numbers in the spleen, liver, and bone-marrow. Some of the pathological effects (piroplasmosis) in the white rat, due to this parasite, were anaemia, biliary fever, alopecia, emaciation, ulcers on the ears and tail, enlarged spleen, &c., and proved fatal. The genus Piroplasma is of great interest, as species of it give rise in various mammals to serious diseases, usually of the nature of biliary fever. P. bigeminum is the pathogenic agent of Texas Fever (Redwater) in cattle; P. canis of malignant jaundice in dogs; P. equi of biliary fever in horses; and P. ovis of similar diseases in sheep. Piroplasmosis may also occur in the human subject, e. g. P. hominis is found in the blood of persons suffering from Spotted or Tick Fever in the Rocky Mountains ; while the Leish man-Donovan bodies found in cases of " Kala-azar" and Delhi boil in India are referred by Laveran and Mesnil to this genus, as P. donovani. A Piroplasma has also been stated to have been found in the blood of certain lizards in India, though details have not yet been published. The symptoms in the white rat seem to exhibit a combination of those enumerated in other mammalian hosts. Piroplasmosis is usually disseminated by ticks; but no ticks have yet been found on infected white rats. Perhaps the intermediate host in this case is a louse or a flea. No flagellates were found in citrate cultures of the blood of infected white rats, though Capt. Rogers, I.M.S., has obtained flagellates from cultures of P. donovani. Mr. Oldfield Thomas, F.R.S., F.Z.S., exhibited the tail-vertebrae of a Dormouse of the genus Eliomys recently received by the British Museum from Central Asia, and stated that it appearie to represent a case of regeneration similar to what occurred in |