424 BOTANICAL GAZETTE [JUNE 
as WAGER (45) holds, as evidence for the idioplasmic nature of 
the latter. The growth of the chromosomes from one cel] genera- 
tion to the next is still too obscure a subject to permit the use of 
such an interpretation. 
As noted above, STRASBURGER (40), as a result of his work on 
Marsilia, in which he found the nuclear reticulum very poor in 
chromatin while the nucleolus was very large, holds the view that 
the linin may be the bearer of hereditary qualities, while the chro- 
matin is only a food substance which divides simultaneously. 
This hypothesis is of interest, and it may be admitted that the recent 
attempts of Boverr (4), RosENBERG (36), OvERTON (34), and 
others to show that the chromosomes are permanent organs of the 
cell may be interpreted in support of the theory that the linin 
substratum of the chromosome is its more essential constituent, 
while the visible and more conspicuous chromatin granules only 
serve as conveniently scattered food. 
Of interest also in this connection is the recent attempt of 
GREGOIRE (20) to show that the nuclear reticulum is all one sub- 
stance, with no differentiation into chromatin and linin. These 
two species of Closterium, and in fact the Conjugatae in general, 
might be regarded as having a nuclear reticulum composed of a 
single substance; still they are perhaps not the most favorable 
material on which to study this question. 
The chromosomes do not come bodily out of the nucleolus of 
Closterium, but that structure disappears during the prophase 
as in other cells, and we have as yet only theories as t nS 
fate. In the present case the theory based on the observations of 
MOLL (32), Mitzkewitcu (31), KArSTEN (25), BERGH (2), and 
others, that as in Spirogyra the chromosomes are included morpho- 
logically complete in the nucleolus, would not be of service in these 
species of Closterium. In like manner the observations of VAN 
WISSELINGH (43) on Spirogyra and of Miss MERRIMAN (29) on 
Zygnema, that a number of the chromosomes come out of the 
nucleolus, would not apply in the present case. While the evidence 
in Closterium is not at all complete, the conclusion reached 
Escovez (12, 13) on Zygnema and Stypocaulon would seem to nile 
most in line with my own observations. These are, that W 
