539 
staining granules and the fibres extending outwards from them, but 
also a wide-meshed network of achromatic figures resting upon the 
surface of the centrosome and uniting the various granules. 
A centrosome somewhat similar to that just described has been 
described by Hicker’) from the winter-egg of Sida, in which, up 
to the time of formation of the equatorial plate, the centrosome appears 
as a dark spot occupying the centre of the astrocoel, but later it 
becomes a vesicle and is surrounded by a faintly staining zone. Almost 
the same conditions obtain in Fulgur, except that in the prophase 
the centrosome consists of several granules, and in the final stage 
which I observed, and which is a little later than that figured by 
HÄcKER, the faintly staining zone surrounding the centrosome is not 
visible, though it is probably represented in the equatorial plate stage 
of Fulgur by the faintly staining material in which the granules 
are imbedded. Hicker finds in the phenomena he has observed a 
confirmation of the chemotactic theory of karyokinesis which Srras- 
BURGER has propounded. I do not propose to discuss this theory 
here, but would point out that in Fulgur the rapid increase in size 
of the centrosomes and astrocoels begins just when the formation of 
the equatorial plate is completed, i. e. just when the movement of 
the chromatin towards the equator of the spindle ceases. It would 
be interesting to know if, from the resting stage to the formation of 
the equatorial plate, there is a constant diminution of the size of 
the centrosomes and astrocoels, just as later there is a marked in- 
crease. 
Anatomical Laboratory, University of Michigan, 
September 17th 1896. 
Nachdruck verboten. 
Zur Kenntnis der Frettchenplacenta. 
Von Prof. H. Srrant in Gießen. 
In einer Reihe von Arbeiten, welche die erste Anlagerung des 
Eies an die Uteruswand bei verschiedenen Tierformen behandeln, habe 
ich den Nachweis zu bringen versucht, daß die während dieses Ent- 
wickelungsvorganges auftretenden Syneytienbildungen aus Umwand- 
lungen des Uterusepithels hervorgehen; ein Teil des letzteren wird 
1) V. Häcker, Ueber die Bedeutung der Centrosomen. Arch. f. mikr. 
Anat., Bd. 42, 1893. 
