RECENT RESEARCHES ON OOGENESIS. 5938 
but usually distinctly non-cellular, have been observed in the 
ova of many animals. Such cases are discussed at length in a 
recent memoir by Sabatier (3) (1884). His own observations 
relate especially to the ova of Buccinum and Lymneus, in 
which besides an extrusion of protoplasm associated with the 
formation and division of a nuclear spindle (polar cell forma- 
tion), other protrusions of an apparently subordinate nature 
may occur. Globules are extruded at various positions on the 
surface of the ovum, for instance at the pole opposite to that at 
which the polar cells appear, and these expressed globules may 
multiply by division outside the ovum. Sabatier maintains 
the occurrence of what he calls centrifugal movements of 
portions of the protoplasm in the ova of both Vertebrates and 
Invertebrates, e.g. Holothuria, Helix pagurus, Geo- 
philus, Rana, &c., and interprets numerous observations in 
terms of his theory, e.g. such phenomena as follicular cell 
formation, in which, as we shall see, he maintains an intra- 
vitelline but non-nuclear mode of origin. He distinguishes 
three kinds of globules. 
(1) Globules précoces ou du début.—Initiatory extru- 
sions, which usually form the elements of the follicle. 
(2) Globules tardifs.—Late extrusions shortly before the 
maturation of the ovum. 
(3) Globules de maturation parfaite.—Differing from 
the two preceding in being associated with karyokinetic 
changes in the nucleus, which remains passive and central in 
the two preceding cases. These are the true polar cells. 
(3 a) In some cases elements are extruded at maturation 
without nuclear participation. 
Sabatier traces the history of these different extrusions. 
(1) The initiative bodies or ‘“ globules précoces” in the ova 
of Ascidians, Vertebrates, some Molluscs, some Aunelides, 
Gephyreans, Arthropods, &c., form outside the egg either 
irregularly distributed masses of granular protoplasm or a 
complete envelope. In other cases they disappear very soon, 
disorganised and reabsorbed, between the ovum and the sur- 
rounding capsule. 
