28 
REPORT OF THE MALARIA EXPEDITION. 
seems much more likely that the life of the individual gametocytes, both male and female, ceases 
with the sexual function in the cavity of the insect's stomach, and that at that moment the life of a 
new bion — the zygote — begins. The gametocyte and the macrogamete are not identical. The 
ft)rmer contains the latter. Perhaps this fact is best indicated by the presence of those minute 
spherical appendages, which have long been observed in coiuiection with the parasites after they 
escape from the enclosing corpuscle, and which Professor Herdman suggests may be the 
homologues of polar bodies. Thus the female gametocyte really contains several cells, only one of 
which, however, reaches full development as a macrogamete. Similarly the male gametocyte 
also contains several cells, only one of which becomes mature and gives rise to the microgametes. 
Hence it is not the female gametocyte, but the progeny of the female gametocyte, which is 
fertilized, and this fertilized progeny constitutes a new individual, which passes its existence in 
the tissues of the gnat. That the macrogamete retains a portion of the tissues (containing the 
melanin) of its parent gametocyte is not inconsistent with biological laws ; but it should be noted 
that, according to Mac Galium, the zygote of one avian species of the Hasmamoebidae actually does 
discard the melanin of the parent gametocyte. 
Hence it would seem that the Hasmamoebidje are organisms which exhibit the phenomenon 
of "alternation of generations." Their full life-cycle consists of two stages — one passed principally 
in the vertebrate liost ; the other entirely in the insect host. 
Mannaberg's idea that two or more amoebulae in one corpuscle conjugate, has found support 
from the observations of one of us in connection with H. rellcta. It seems possible that the 
gametocytes are produced by such conjugation. At any rate, it is difficult to understand what else 
but conjugation can happen to two or more amcjebula; in this position. 
It is very noteworthy that, while Europeans who come from the West Coast of Africa 
suffering from gnat-fever often contain large numbers of crescents, these bodies could scarcely be 
found at all in Freetown. This experience tallies with the observation of one of us in very 
malarious districts in India [21]. It would seem that gametocytes cease to be produced, at least in 
large numbers, when an infection has lasted a long time — as for instance more than six months or 
a year. This may be explained on the supposition that the number of parasites tends to diminish 
as a case advances, owing to gradual production of partial individual immunity, and that it is 
therefore rare to find two amoebulas in one corpuscle in old infections. Of course, in very 
malarious localities the majority of cases are old infections ; whereas patients who resort to the 
Tropical Ward in Liverpool are generally comparatively recent cases [22]. 
We have used the taxonomical nomenclature previously suggested by one of us [15]. It 
is as follows (inclusive only of the parasites of men and birds) : — 
Family : HiEMAMCEBiDiE, Wasielewski. 
Genus I. Hretnamasbciy Grassi and Feletti. The mature gametocytes arc similar in form 
to the mature sporocytes before the spores have been differentiated. 
Species i : Heemamceba danilewsk'ti^ Grassi and Feletti. Syn. : Laverania danllewskii^ 
' Grassi and Feletti, in part ; Halter'idium dani/ews^ii, Labbe ; etc. Several 
varieties — possibly distinct species. Parasite of pigeons, jays, crows, etc. 
