TETRAD AND EMBRYO-sAC MITOSES 83 
3. Centrosomes or centrosome-like bodies are not present. 
The poles of the spindle are finely tapering points with various 
topographic relations described in the body of the text. The sug- 
gestion made by Meves, prompted by his observations on Paludina, 
is not pertinent. 
Under certain conditions, as for example in the pollen-mother- 
cell, where the proportions of the cell are not too great relatively 
to the size of the nucleus, the spindle ends find an insertion in the 
ectoplasm. At the point of insertion a small thickening may fre- 
quently be seen, and from this point run out radially placed, 
branching fibers in the ectoplasm. It is suggested that these are 
currents in the ectoplasm and may represent kinoplasm passing 
from the spindle into the ectoplasm during anaphase. 
4. At the end of the first and second embryo-sac-mother-cell 
divisions, and at the end of the third division also when such oc- 
curs, as is generally the case in Crucianella, a system of connecting 
fibers arises without, however, the formation of cell walls. The 
megaspores and their derivatives in Crucianella remain in a syn- 
cytial condition. 
5. A reduced number of chromosomes appears in the prophase 
of the first division of the pollen- and embryo-sac-mother-cells ; 
in Crucianella this number is ten; in Asperula twelve. These 
numbers are maintained 7 the subsequent ۰ 
The prophase of this division is characterized by the stage 
known as diakinesis. The metaphase offers on the whole the 
same characters as have been described by a number of authors for 
various plants and differs from them only in points of detail refer- 
able to the proportions of the chromosomes. The frequently dif- 
ficult observation of the so-called ring form of the chromosome 
pairs in metaphase isa case in point. When the chromosomes are 
relatively more slender, as in the Liliaceae, the appearances are 
relatively more distinct. In many other plants they are less so 
on account of the extreme shortness and thickness of the chro- 
mosomes. 
The second splitting of the chromosomes is longitudinal, and 
takes place in Asperula during the late anaphase of the first di- 
Vision. In Crucianella a similar splitting of the chromosomes 
takes place in the telophase of the first division and is here also 
longitudinal. 
