310 PHILLIPS—A REVIEW OF PARTHENOGENESIS.  [Oct. 16, 
the first polar nucleus conjugates regularly with the second polar 
nucleus and forms a ‘‘ Richtungscopulationkern,’’ with the nor- 
mal number of chromosomes. ‘This nucleus in the drone egg gives 
rise by three divisions to eight cells with double nuclei. In ferti- 
lized ova and in drone eggs laid by fertile workers this nucleus 
forms a spindle, which either simply disappears or gives rise to a 
number of nuclei, one to four; but these always show disruption 
phenomena in the chromosomes and ultimately disappear. In a 
later paper the same author (Petrunkewitsch, 1902) asserts that the 
products of the Richtungscopulationkern ultimately become the 
testes of the adult drone. 
Paulcke (1899) found that in drone eggs there are four groups of 
chromosomes. Of these two seem to be the result of division of 
the first polar nucleus, one of the second polar nucleus and the 
fourth the egg nucleus. In twelve eggs examined from worker 
cells, fifteen minutes after they were laid, eight show sperm nuclei 
with their radiating systems. In eight hundred drone eggs exam- 
ined no sperm nuclei were seen, but in three cases dark corpuscles 
were observed, which might have been sperm nuclei. In fertile 
worker eggs there were no indications of male pvro-nuclei. 
Mrazek (1897) and Erlanger und Lauterborn (1897, studied the 
maturation of the eggs of Asplanchna, a Rotifer. They find in 
this genus three kinds of eggs: (1) Parthenogenetic male eggs; 
(2) parthenogenetic female eggs, and (3) female eggs which require 
fertilization. When the female eggs requiring fertilization begin 
to develop, all other eggs begin to show cleavages of a degenera- 
tive nature, not like the normal cleavage, probably due to lack of 
nutrition (Mrazek). The parthenogenetic female eggs give off one 
polar body which never divides, while the parthenogenetic male 
eggs give off /wo polar bodies, the first of which normally divides. 
The female eggs requiring fertilization act like the parthenogenetic 
male eggs. In the parthenogenetic male eggs there is no indica- 
tion of a union of the second polar body with the egg. The num- 
ber of chromosomes is not determined (Erlanger und Lauterborn).’ 
Riickert (1895) found that in Cyclops sternuus the second matura- 
tion division cuts off a polar nucleus which remains in the egg, in a 
direction tangential to the second division figure. It does not 
. 
1See also Lenssen, 1899, ‘* Contribution & l’Etude du developpement et de 
la maturation des ceufs chez 7? Hydatina sexta,” Cellule, xiv, pp. 421-51, 2 pl. 
