36 WHITMAN. [VoL. Il. 
of the polarity of the egg, and would leave inexplicable the differ- 
ence between telolecithal and controlecithal eggs. Besides, this 
view assumes that the pronuclei are homodynamous, a point 
which cannot be conceded, since male pronuclei do not behave 
towards one another as they do towards female pronuclei. 
A special feature in the polarity of the fish egg, noticed by 
Kupffer and by Hoffman? (p. 88), is the formation of a tem- 
porary discoidal thickening (‘Gegenhiigel,’ Kupffer) at the veg- 
etal pole. Here, then, is a disc-formation at the point farthest 
removed from the nuclear bodies, and this fact appears to be 
fatal to the above theory. We are reminded of the rings in the 
egg of Clepsine, and their concentration into two polar discs. 
It appears not improbable that the two sets of phenomena are 
similar in nature, and determined by like forces. In the fish 
egg the disc-formation is not preceded by a ring-formation ; and 
the nearest approach to the ring-rays are the ‘radiating bands’ 
or ‘beaded streams’ described by Ryder! (p. 17). 
Raffaele (Mitth. d. Zool. Station z. Neapel, VIII., 1, 1888) has 
recently described a very singular phenomenon in the egg of 
Labrax. The egg has a single large oil globule at the pole op- 
posite the germinal disc. This oil globule is enveloped with 
protoplasm, which, on the side facing the germ, thickens up 
until it takes the form of a long club-shaped body. This body 
elongates in an axial direction, and the distal portion, which is 
gradually constricted off, eventually assumes a globular form 
and rests on the inner face of the germ. Ryder has noticed 
protoplasmic bodies in the egg of Gadus (‘segmenting corpus- 
cles’) which, as Raffaele suggests, may have a similar mode of 
origin. It occurs to me that this body of protoplasm may cor- 
respond to Kupffer’s ‘Gegenhiigel,’ and that it is diverted 
from its usual peripheral track by the presence of the oil globule. 
The Artificial Division of Infusoria. — The artificial divis- 
ion of infusoria has been resorted to as a. means of decid- 
ing, experimentally, the question of the relative importance 
of the nucleus. M. Nussbaum!® was the first to establish 
15 Die Entwickelung des Herings im Ei. Fahresh. d. Comm. z. wiss. Unter- 
suchung der deutschen Meere in Kiel, 1V.—V1., 1874-1876. 
16 Zur Ontogenie der Knochenfische. Amsterdam, 188t. 
17 The Embryography of Osseous Fishes. Report of the Commissioner of Fish 
and Fisheries for 1882. 
18 Die spontane und kiinstliche Theilung der Infusorien. Arch. f. mik. Anat., 
