No. 2 .] COMPARATIVE CYTOLOGICAL STUDIES. 509 
gory should not be classed small masses of nucleolar substance 
grouped around a larger one, these being normal phenomena 
during the growth period of nucleoli. 
Reticulations within the nucleolar substance have been de¬ 
scribed by some few authors. Thus Carnoy (’85, ’97a), Meunier 
(’86), and Moll (’ 93 ) described nucleoli containing a skein of 
chromatin, but Zacharias and Strasburger (’88) did not find 
anything resembling these supposed skeins described for 
Spirogyra. Leydig (’88) states that the germinal spot of Lycosa 
“ bietet das Bild eines Knauels dar.” Fromann (’84) described 
the nucleolar substance as consisting of granules connected by 
fibers, Butschli (’80) found the nucleoli of Dinoflagellata to 
contain a fine reticulum, and Davidoff (’89) states that the 
germinal spot of Distaplia takes up portions of the nuclear 
reticulum into itself (but cf. Bancroft, ’98, and Shafer, ’80). The 
only structure which was found by me to resemble a skein was 
present in the later stages of the germinal spot of Polydora ; 
but in this object, owing to the gradual confluence of the vacu¬ 
oles, which thus produce anastomosing channels of vacuolar 
substance in the ground substance of the nucleolus, it is the 
true ground substance which represents a skein-like appear¬ 
ance. It is very probable that Carnoy and his followers have 
mistaken the vacuolar substance for the ground substance, and 
have considered the true ground substance to be chromatin ; 
I am forced to conclude that in all probability there are no 
skeins of chromatin lying in any metazoan nucleolus, since I 
have never found any evidence of chromatin in it in any meta¬ 
zoan cell. But it is not improbable that in the nuclei of 
gregarines chromatin may be massed in some or all of the 
nucleoli. 
Nucleolini, granules within the nucleolus, have frequently 
been observed. A single nucleolinus to a nucleolus has been 
described by Vejdovsky (’95b), Morgan (’96), Agassiz (’ 57 ), 
Kleinenberg (’ 72 ), Leydig (’88), Macfarlane (’85), Lavdowsky 
(-98), A. Brandt (’78), Van Bambeke (’86), Kosinski (’87, 33 ) ; 
several nucleolini to a nucleolus, by Burger (’ 90 ), Rhumbler 
(’93), Holl (’93), Wolters (’ 91 ), Schron (’65), Scharff (’ss), See- 
liger (’82), Gjurasin (’93), Haeckel (’ 74 ), Mann (’ 92 ), Van Bam- 
