312 Wisconsin Academy of Sciences, Arts, and Letters. 
studies on Podophyllum that the doubleness of the early pro- 
phasic somatic nuclear chromatic elements is due to the lateral 
association of the parental elements rather than to a splitting of 
the telophasic chromosomes. 
As I have stated in my previous work (Overton, ’09a), the 
nucleus is not only double in the sense that it contains two sets of 
parental chromosomes, but these chromosomes are so placed that 
there may be an interaction between homologous parallel pairs, 
and the association of homologous chromosomes probably occurs 
during fertilization or shortly thereafter, although the actual in¬ 
terchange or mutual influencing of parental parts occurs during 
synapsis or related stages. It may further be added that the se¬ 
rial paired arrangement of homologous parental elements in so¬ 
matic cells suggests the probability of mutual interaction and in¬ 
fluence throughout the life history of the sporophyte. From my 
present studies on Podophyllum and from a detailed study of the 
literature I can find nothing to cause a change of view. 
Since the above was written an important note by de Litardiere 
(’21) has appeared, dealing with the structure and behavior of 
the chromosomes in the root tips of Podophyllum peltatum. Cer¬ 
tain results as stated in this note do not agree with my (’09 b) in¬ 
terpretation. In my preliminary report it was stated that the 
alveolation of the chromosomes occurs during the passage of the 
anaphasic chromosomes toward the poles and that there was evi¬ 
dence that there were two substances in the chromosomes, the 
chromatic granules being separated by a progressive vacuolation 
of a linin ground substance. De Litardiere holds that the alveo¬ 
lation begins as early as the anaphasic dissociation, alveoli being 
visible in only slightly stained sections. As stated in the present 
paper, I have observed the beginnings of vacuolation as early as 
the metaphase. I still maintain that the chromosomes are com¬ 
posed of two substances, as previously stated. De Litardiere de¬ 
scribes an axial row of vacuoles in each chromosome separated from 
each other by thin partitions. As a general prenomenon, I have 
never observed the appearance of such an axial arrangement of 
vacuoles. One can often find individual chromosomes with such 
a row of granules, but it is not the usual appearance in what I 
regard as well fixed material. I have found the alveoli scattered 
at all times so that the alveolar-reticulate bands have a spongy 
appearance, as described in Gregoire. 
At the poles and during the telophase stages, de Litardiere de- 
