1905. | ON REGENERATION OF THE TAILS OF MICE. 49] 
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. Hach branch bore its own four 
rows of sete. 
Mr. H. B. Fantham, B.Sc., F.Z.S., exhibited and made the 
following remarks upon microscopic preparations of a new 
Hemosporidian parasite belonging to the genus Piroplasma, from 
the blood of the white rat :—The parasite is endoglobular and the 
trophozoites are ovoid (0°5 to 1:5 » in diameter) or pear-shaped 
(2 to 3p long and 1 to 15 broad), and usually uninucleate. 
A single pear-shaped trophozoite often occurs alone in a blood- 
corpuscle of the host. Some amceboid 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 anemia, 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. LP. bigeminwm 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 Leishman-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 inter- 
mediate 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. donovan. 
Mr. Oldfield Thomas, F.R.S., F.Z.S., exhibited the tail-vertebrze 
of a Dormouse of the genus Hliomys 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 
