24 Gen. Sub. 
GENERAL SUBJECTS. 
Hertwig, 0. Experimentelle Studien am tierischen Ei vor, wahrend, 
und nach der Befruchtung. Jen. Z. Nat. xxiv, pp. 268-313, 3 pis. 
Delayed spawning of Echinus microtuber culutus and Strongylocentrotus 
lividus seemed to make the ova pathological. Some would not fertilize 
at all ; many were susceptible to multiple fertilization ; segmentation, 
if it began, was pathological. Influences of lowered temperature on 
segmenting ova. Ova of Strongylocentrotus may take up methyl blue 
pigment, and this can be seen in the blastula stage. Ova of starfishes may 
begin to segment without fertilization. 
Hertwig, O. Vergleich der Ei- und Samenbildung bei Nematoden. 
Eine Grundlage fur cellulare Streitfragen. Arch. mikr. Anat. xxxvi, 
pp. 1-138, 4 pis. 
The mother sperm-cell is the homologue of the immature ovum. 
During a prolonged resting-state, the nuclear substance in both is peculi- 
arly prepared for two successive cell -divisions. The homology holds true 
throughout. The two daughter-sperm-cells correspond to the ovum and 
the first polar body ; the four spermatozoa are equivalent to the ripe 
ovum, the second polar body, and the two spheres arising from the 
division of the first ; the polar bodies have the morphological rank of 
rudimentary egg-cells. They are abortive ova ; their production is com- 
parable to that of spermatozoa from a mother-sperm-cell ; their persist- 
ence is explained by the physiological importance of the reduction which 
they effect in the mass of the germinal vesicle. 
Hickson, S. J. On the Maturation of the Ovum, and the Early Stages 
in the Development of Allopora. Q. J. Micr. Sci. xxx, pp. 579-598, 
i pi. 
It seems probable that the “ trophodisc ” is not a reduced Medusa. 
The oosperm nucleus undergoes fragmentation. Ova and young embryos 
are found in the younger branches ; the sperm-morulae and sperms in the 
older branches. The ovum pushes out the endoderm and ectoderm of 
the canal in which it is formed, and makes for itself a diverticulum. 
Holl, M. Ueber die Reifung der Eizelle des Huhns. SB. Ak. Wien, 
xcix, pp. 309-370, 1 pi. 
The vitelline membrane or tunica adventitia, the follicular epithelium 
or membrana granulosa, and the membrana propria, all arise from the 
stroma of the ovary. The nucleus undergoes considerable changes 
during maturation. The zona radiata is a product of the cells of the 
membrana granulosa. 
Janosik, J. Bemerkungen fiber die Entwicklung des Genitalsystems. 
T. c. pp. 260-288, 1 pi. 
Kastschenko, N. Ueber den Reifungsprocess des Selachiereies. Z. 
wiss. Zool. 1, pp. 429-442, 1 pi. 
During maturation of ova in Pristiurus , Torpedo , and Scy Ilium, the 
polar globules are formed by karyomitotic division ; one is separated off 
in the ovary, and the other probably at the time of fertilisation. 
