2l8 
ZOOLOGY: D. H. TENNENT 
Proc. N. a. S. 
of chromatin in the cytoplasm have been interpreted as chromidia, or as 
trophochromidia. Schaxel (1911) in a series of able papers, has presented 
evidence in support of the idea of emitted chromatin; Dantchakoff's 
(1916) observations support the idea. On the other hand Beckwith 
(1914), by no means denying, and Gatenby (1919), strongly supporting 
the idea of emissions from the nucleus, find no evidence of the emission 
of formed materials, in the sense of filtration of chromatin through the nu- 
clear membrane. 
There have been no observations which have enabled us to link, in any 
satisfactory way, our theories concerning the synthetic activities of the 
nucleus with the observations of Chambers (1917) on reversible changes 
in the cytoplasm, and with other knowledge of colloidal solutions. The 
material on which this paper is based makes an attempt at such a linkage 
possible. 
In 1908 {Biol. Bull, 15, p. 132), in discussing sections of Arbacia eggs 
fertilized by Moira sperm, an inter-ordinal cross, I wrote, "In eggs in which 
the daughter nuclei are in the resting condition succeeding the first division, 
the cytoplasm contains many deeply staining rods. The nucleus at this 
time does not take the chromatin stain and appears like an empty vesicular 
structure." 
"In eggs of the same lot and on the same slides, in which the fibers 
of the second amphiaster have begun to form, the nucleus again takes the 
stain and shows the chromatic net, while the cytoplasm is seen to be free 
from the bodies described." 
"These structures have puzzled me not a little, but I have finally reached 
the conclusion that the eggs in which they occur are degenerating. Even 
though this be true it is difficult to explain the simulation or perhaps 
occurrence of longitudinal and transverse divisions of these chromosomes 
lying free in the cytoplasm." 
The facts were so unusual that in 1911 I prepared and later studied a 
more complete set of material. One of my graduate students, Miss 
Pauline Shorey, also sectioned and studied duplicate stages, but it is not 
until recently that I have been willing to venture an explanation. 
The material comprises ten stages, taken at short intervals through a 
period extending from 25 minutes after insemination to 100 
minutes after insemination, or through the anaphases of the 
third division. Unfortunately, from the point of a study of cytoplasmic 
inclusions in general, but especially of mitochondria, but one fixing fluid, 
acetic sublimate (5% acetic), was used. Nevertheless, as the straight 
fertilized Arbacia eggs used for comparison were fixed in the same way, 
the opportunity for a sound and logical comparison exists. The sections 
on which the greater part of the study was made were stained in Heiden- 
hain's iron-haematoxylin, but for the determination of special conditions 
Auerbach's acid fuch sin-methyl green, basic fuchsin, basic fuchsin-methylen 
