24 PAULINE H. DEDERER 
zone C contains very small nuclei similar to A, arising chiefly 
from the cells of zone B by amitosis, and giving rise to the ova. 
They believe amitosis plays an important role. No cell bound- 
aries appear in these zones. In young ova, leptotene threads 
are seen, followed by a stage of broken spireme threads. These 
gradually disappear, and reappear later to form chromosomes. 
The figures given are chiefly photographs and do not adequately 
illustrate the points mentioned in their paper. The importance 
of amitosis has been questioned by Gross (’01), who concluded 
from his studies on Hemiptera that nuclei which divide amitoti- 
cally never divide again by mitosis. 
Payne (’12) also discusses the origin of the ova in Gelastocoris, 
another hemipteran. He finds the same three kinds of cells, 
although their arrangement in zones is very indefinite. He is 
convinced that the eggs are not derived from the small nuclei 
of zone C, but from certain larger cells of zone B, which he finds 
in synapsis, and that there is no break in the continuity of the 
cells from oogonia to ova. This appears to be a more reasonable 
interpretation of the development of the eggs, and accords more 
closely with the conditions observed in other insects. 
Coleoptera. Debaisieux (09) has described the early oogen- 
esis in Dytiscus marginalis, amplifying Giardina’s work on the 
same form. Debaisieux discovered a synaptic and a diplotene 
stage between the zone of differentiation of eggs and nurse cells 
and the growth zone. In the latter, the chromatin of the nurse 
cells gives rise to tetrads which fragment, the chromatin of the 
egg cell remaining in the diplotene stage as before. His main 
conclusions are, (1) that the ‘chromatic mass’, which Giardina 
believed to be derived from certain chromosomes is not true 
chromatin, but a condensation of the reticulum left in the nu- 
cleus after the chromosomes of the last oogonial division are 
formed; (2) that the chromosomes persist autonomously up to 
the maturation divisions. In Ginthert’s paper (10) the chief 
point of interest is the description of differential mitosis in the 
oogonia. When a cell divides, a ‘chromatic mass’ and the 
spherical remains of the spindle pass into one cell undivided. 
This becomes the egg cell, which again divides differentially 
