REPORT OF THE MALARIA EXPEDITION. 
27 
to employ these terms as indicated. We may admit that, strictly speaking, the blasts are also 
spores, while the spores are, in a sense, also blasts ; but it will certainly be convenient in tlic 
present case to apply the word spore only to the asexually-produced progeny, and the word 
blast only to the sexually-produced progeny. 
Obviously the zygote is the homologue of a fertilized ovum ; and tlic blasts are iiomo- 
logues of the cells which spring from the fertilized ovum, and which construct tiic tissues of 
multicellular organisms. Only, in this case the blasts give rise, not to a cluster of cells, but 
to a cluster of distinct unicellular animals — by a kind of polyembryony in fact. Hence tiie 
use of the word " blast " for the progeny of the zygote appears to derive sanction from the homo- 
logous use of the same word in embryology. The word "zygote" seems to be acquiring the 
restricted meaning of the result of union of two similar gametes ; we use it as often applied, 
namely, to express the result of union of any two gametes. 
Of course other terminologies may be preferred by some. Professor Ray Lankester has 
recently been kind enough to suggest terms, which bear the weight of his authority and may 
be liked by many. He suggests " androspore " and " gynospore " for microgamete and 
macrogamete respectively — terms certainly much more definite ; " gametospore " for zygote ; 
" nomospore " for the asexually-produced spore; " oudeterospore " for any spore which is not 
differentiated so as to be male or female ; and " gametoklasts " or " gametoblasts," or even simply 
" filiform young," for the blasts. 
Manson was the first to interpret rightly the ascertained facts about the sexual propagation 
of the parasites, and his views have been adopted by other writers ; but he has attempted no 
terminology. Grassi and Dionisi use " gamete," " microgametogene " (for microgametocyte), 
and zygote [19]. The term gamete had been previously applied by Sciiaudinn and Siedlecki to 
the case of some of the Coccidiidae. The Italian observers also use the word " sporozooids " 
for the blasts. 
Koch employs simply "spermatozoon" for microgamete [11]. The zygotes he calls 
"spherical bodies (Kugelformige Gebilde) " ; the meres, "secondary spheres"; and the blasts, 
" sickle-shaped bodies (Sickelkeime)." 
The terms " sporozooid " and " sickle-shaped body " suggest somewhat doubtful analogies 
with the Coccidiida;. The former term, moreover, is not very intelligible — sporozooids being, in 
fact, spores ; while the so-called spores of the sporozoa are really often sporocysts. Compare also 
Mesnil [20]. 
The simple expressions ovum and sperm may be preferred by many to macrogamete and 
microgamete. Professor Harvey Gibson suggests " oosperm " — that is, the combined ovum and 
sperm — for zygote. The word " zooid " has been suggested in the place of blast ; but zooid has 
the acquired meaning of a motile cell, and we do not yet know that the blasts are motile. 
A biological point of some interest requires reference. Several writers seem to assume that 
the zygote in the gnat is the same individual organism as the female gametocyte in the vertebrate 
host — tliat it is, in short, the fertilized female parasite. This idea receives some support from the 
fact that the zygote contains the melanin of tlie gametocyte. On consideration, however, it 
