SPERMATOGENESIS OF EUSCHISTUS 749 
I. The actual reduction of the number of the chromosomes is 
effected during the prophases of the maturation mitoses, and both 
of these divisions are equational. This was originated by Boveri 
(87) and Brauer (’93). To-day it is held in two forms: (A) 
Meves (’96,’07a) Fick (’07,’08), and Duesberg (’08) argue that a 
continuous spirem is produced, that this segments into half the 
normal number of chromosomes, the cleft along such a bivalent 
chromosome being a true longitudinal split; they reason there is 
neither metasyndetic nor parasyndetic conjugation of chromo- 
somes. (B) Bonnevie (’06,’08) and Vejdovsky (’07) hold there is a 
parasyndetic union of chromosomes, but that this conjugation 
leads to complete and persisting fusion. 
II. The reduction of the number of the chromosomes is 
effected by the maturation mitoses, one at least of which is a 
reduction division. There are several variants of this, as follows: 
A. The univalent chromosomes, without conjugation or 
pseudoreduction, double their number during the prophases 
then become quartered in number by two successive reduction 
divisions. This view was founded especially by O. Hertwig 
(90) and Wilcox (95). . 
B. The univalent chromosomes undergo neither conjugation 
nor pseudoreduction during the prophases, but conjugate first in 
the equator of the first maturation spindle, and there separate 
reductionally. Founded by Henking (’91) and Korschelt (’95). 
C. The univalent chromosomes undergo pseudoreduction in 
the prophases by a continuous chromatin spirem segmenting into 
half the normal number of segments; these divide equationally 
in the first mitosis, and reductionally in the second; Rickert 
(793, ’94), Hacker (’95), Vom Rath (95). 
agreement need mean nothing in itself, but the more serious objection is that 
Hicker has tried to analyze the phenomena to large extent from a study of the 
maturation mitoses, without special regard to that most important series of stages 
found only in the growth period. Accordingly, Hacker’s conclusions cannot 
be considered in any measure founded until he has filled in this gap, for every one 
must recognize how elusive it is to argue phenomena of change simply from the 
phenomena of behavior of the definitive gemini. 
JOURNAL OF MORPHOLOGY, VOL. 22, NO. 3 
