The relation of nucleoli to cliromosomes in the egg of Cribrella sanguineolenta etc. 405 
crons. Both the egg of Cribrella and its nucleus have a diameter appro- 
ximately six times as great as that of the egg and nucleus of Asterias. 
The larger size of the egg of Cribrella involves a larger nucleus and 
may demand more nuclear chroraatin. The latter is present in the form 
of very many secondary nucleoli of varying sizes. The evidence here 
seems to indicate that cell size is a function of chromatin mass as held 
by Boveri. But not all of this nucleolar material goes to form chromo- 
somes. The important question as to the physiologic difference between 
the chromatin that goes into the chromosomes and that which is resorbed 
by the cytoplasm still remains. The simplest hypothesis, again, and 
one to which there appears the least objection seems to be that the cliro- 
matin in both instances is of the nature of nutritive material. 
It will furnish an interesting point in a further comparative study 
of Asterias and Cribrella to confh'm or refute the second portion (applied 
in a wide sense) of Boveri’s law, viz. : that the cell volume is directly 
proportional to the chromosome number. If this law prevailed as regards 
the two asteroid forms Asterias and Cribrella we should expect to find a 
very great number of chromosomes in the latter, as I had pre\’iously 
concluded for Echinaster, or perhaps very large chromosomes. Nothing 
definite can be said at present regarding the chromosome number or size 
either in Cribrella or Echinaster. This matter must wait for a contem- 
plated study of the maturation stages. It appears more probable though, 
from the slight evidence that can be derived from a study of the sperma- 
togenesis of Cribrella, that the specific chromosome number does not 
exceed the usual (for a number of Echinoderms) somatic complement 
of 36. Among different Orders and families (e. g., Toxopneustes, Asterias 
and Cribrella) cell size and the amount of nuclear chromatin appear to 
bear a certain relationship to each other; but it would seem that this 
relationship does not necessarily involve the number or size of chromo- 
somes. 
