Minutes of Proceedings. xix 
The paper contains full descriptions of the twenty-three known species 
of the African genus Alepidea, of which eleven are described as new. 
One of the new species — A. Thodei — is figured. 
"Positive Electrical Change in Isolated Nerve," by Professor Jolly. 
The various theories which have been put forward regarding the 
causation of positive electrical change in isolated nerve are critically 
discussed, and the results obtained by different instruments and methods 
of investigation correlated. The positive after-variation is differentiated 
from positive change produced during a period of stimulation, and is 
regarded as depending on two factors : (1) a process occurring in the 
uninjured part of the nerve subsequent to excitation, and (2) increase 
in demarcation current. 
" A Short Note on the Occurrence of a Leucocytozoon Infection. 
Host : the Ostrich," by James Walker. 
In November, 1911, when investigating the cause of the mortality 
amongst ostrich chicks on a farm in the Middelburg District, Cape 
Province, the presence of a Leucocytozoon infection was noted in some 
instances in blood-smears collected from sick chicks. 
The infection has been known to exist on a number of farms in the 
Cape Province, and it was found in 3-4 months' old chicks showing the 
symptoms of anaemia, stunted growth, and loss of condition. Although 
in some cases on post-mortem Strongyli infection was also observed, from 
the microscopical examination of the blood, which showed a gross invasion 
of cells by the parasites, the anaemic condition was, in the writer's opinion, 
attributable to the Leucocytozoon infection. 
Microscopical appearance of the parasite m stained blood- smears. — Two 
main types of the parasite, apparently corresponding to female and male 
gametocyte, have been noted. The female gametocyte occurs most 
frequently. The shape varies, it is more or less rounded, but irregular 
forms are frequent. 
The diameter of the rounded forms is from 4 to 15 microns ; of the 
irregular forms, the size varies from 11 to 15 microns in length, and 
from 9 to 13 microns in width. 
The protoplasm stains deeper than in the case of the male gametocyte 
and scattered throughout it are frequently to be seen a number of meta- 
chromatic granules, which are more distinct in some of the parasites. A 
number of clear spaces appear throughout the protoplasm. 
Situated in different positions, namely, towards the periphery or centre 
of the parasite, is an aggregation of small granules, which apparently 
represents the nucleus, and, lying in the mass of granules or at the edge 
of these, a large chromatin granule, average size 1 micron, which stands 
out distinctly, is seen in most cases. 
The male gametocyte is likewise more or less rounded in shape, but 
