Division in the Root of Victa Faéa. 17! 
We may now give a short review of an article by H. H. 
Dixon, entitled, ‘‘ The Possible Function of the Nucleolus in 
Heredity.”* His conclusions have been derived not only from 
his own work, but from a careful consideration of the views 
of numerous writers. 
The majority of biologists believe that the hereditary sub- 
stance is transmitted in the chromatin of the nuclear thread, 
this suggestion coming first from Strasburger. The above 
writer extends this generally accepted theory. According 
to him, the hereditary substance is contained completely in 
the chromatin elements (chromosomes) during nuclear divi- 
sion, but during the resting stage of the nucleus it is sug- 
gested as probable that the hereditary substance is distributed 
between the chromatin thread and the nucleoli. The heredi- 
tary substances (idioblasts), which determine the attributes of 
the cell in which they are situated, are located in the chro- 
matin thread, while inactive idioblasts are in the nucleolus or 
nucleoli. 
Hertwig says that to prove the above hypothesis four points 
must be considered : 
1. The equivalance of the male and female hereditary 
masses. 
2. The equal distribution of the multiplying hereditary 
masses upon the cells, derived from the fertilized ovum. 
3. Prevention of the summation of the hereditary masses. 
4. The isotropism of the protoplasm. 
The opinion that the substance of the nucleolus is dis- 
tributed along the chromosomes, during the early stages of 
karyokinesis, has been gaining favor. The evidence in favor 
of this view is based on the simultaneous change in the 
amount of nucleic acid in the chromatin and the nucleoli. 
As the latter decreases in amount, the former increases, and 
wice versa. 
1 Annals of Botany, June, 1898. 
