No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
375 
each “ chromosome ” consists of “ two granules, at first of the 
same size [which] grow very unequally, so that one is often 
considerably larger than the other. Hereupon some, but not 
all, of these granules break down to form irregular strings of 
minute karyomicrosomes which are distributed along the fibers 
of the achromatic reticulum. . . , The large chromatin granules 
which do not break down become the nucleoli of the pronuclei. 
I am unable to state positively that in each Diplococcus-shaped 
chromosome one of the granules breaks down to form a chain 
of minute karyosomes while the other persists as a nucleolus, 
but I am very strongly inclined to believe that this is the case.” 
These nucleoli are cast out into the cytoplasm when the first 
cleavage spindle is formed, and there rapidly dissolve. Wheeler 
accepts “Hacker’s view of the secretory nature of the nucleo¬ 
lus, at least so far as the germinal vesicle is concerned.” 
Bancroft (’ 98 ), germinal vesicle of Distaplia: the nucleolus 
“does not form the stellate body found in the old ova, as 
Davidoff maintained, but is found within this body, which is 
itself the remains of the germinal vesicle. The nucleolus at 
this stage is quite complex, consisting of a homogeneous cortex, 
an excentric finely granular medulla, and within the latter 
several very highly refractive bodies, the largest of which may 
have a granular appearance. During the greater part of the 
growing period these refractive bodies are the only substance 
in the germinal vesicle that takes the chromatin stain with a 
methyl green and acid fuchsine combination.” 
1898. 
Kostanecki (’ 98 ) confirms the observations of Wheeler (’ 95 , 
’97) in regard to the casting out of the nucleolus into the 
cytoplasm, in the maturation of the ovum of Myzostoma. 
B . Botanical Literature. 
Schleiden (’ 38 ) is the discoverer of the nucleolus in plants, but 
he gives it no name : “ einen kleinen, sich scharf abgren- 
zenden Korper, der, nach dem Schatten zu urtheilen, einen 
