310 Wisconsin Academy of Sciences, Arts, and Letters. 
phases are accomplished. Sharp points out that his investigations 
on the somatic cells of Yicia show not only that the telophasic 
alveolation of the chromosomes is too irregular to permit of its 
being looked upon as a splitting, but also that the reticulate con¬ 
dition of the somatic prophases, instead of developing directly 
into the definite split, gives rise to simple thin threads in which 
a new split occurs. Sharp ( ’20b) in his work on Tradescontia 
virginiana comes to a like conclusion. 
Although I agree with Sharp that the interpretation of Miss 
Digby has certain advantages, it appears to me that the best so¬ 
lution of the problem is to be found not so much by determining 
the exact manner of telophasic transformation and the derivation 
of the chromosomes from the prophasic reticulum, as by the fact 
that the chromosomes remain distinct throughout all stages of 
the heterotypic and homoeotypic divisions, and that in certain 
cases their complete history both during rest and division can be 
followed. As mentioned, I have found that in the root tips of 
Calycanthus the prochromosomes in the resting nuclei are associ¬ 
ated in pairs and are quite as large as the ordinary somatic chro¬ 
mosomes and have the same shape. In these root tips I have 
also found the definite chromosomes of division associated in pairs 
just as Strasburger (’05) has described them for Funkia and 
Galtonia and as they have since been described by several other 
workers for other forms. I have already pointed out that in the 
vegetative cells of Podophyllum the chromosomes are arranged in 
pairs. The only indication of their doubleness in the early pro¬ 
phases in this plant is due undoubtedly as in other cases to the 
associated chromosomes being in pairs. Of course, as both Sharp 
and I have definitely shown, each chromosome undergoes an ulti¬ 
mate longitudinal split in the later prophases. Although Vicia and 
Podophyllum are favorable subjects for study of chromosome vac- 
uolation and of the prophasic evolution and splitting of the definite 
chromosomes, they are not as well adapted to solve certain phases 
of the problem as are plants with shorter, less definitely reticulated 
chromosomes. In such forms as Funkia, in which Strasburger 
(’05) found the chromosomes of different sizes in pairs not only 
during division but also during the prophases, it should be pos¬ 
sible to find a satisfactory solution of the problem, especially in 
plants in which not only the pairing is evident but the reticula¬ 
tion during rest is small. 
