REACTION OF THE PLANT. 93 
an enlargement of the nucleus, often to double the normal size, and often a change of shape 
to spindle form. In such tissues the nuclei stand out very prominently in the small cells, 
being the most conspicuous objects in the section. This size, however, may be a character- 
istic of extreme youth rather than of disease, since the writer has also seen large nuclei in 
the tissues of the growing point of healthy daisy-plants. The disorganization of the nucleus 
in root-nodules of Leguminosae seems to be 
preceded by some enlargement. The subject 
requires further study. 
CHANGES IN THE CHROMOSOMES. 
Following Farmer’s statements and similar 
statements by other English students of malig- 
nant animal tumors, the writer has been very 
much interested to see whether the chromosomes 
undergo any change in number or location in 
the rapidly dividing cells of crown-galls and 
similar plant tumors. ‘The first studies were 
made on peach tissues but here the nuclei are 
so small that the determination of the normal 
number of chromosomes proved difficult. At- 
tempts to get tumors on onion, the normal 
cytology of which is well known, also failed. 
The Paris daisy was finally selected. This has 
large nuclei and the normal number of chro- 
mosomes appears to be 16. A study of slides 
prepared from very young stages of tumors 
taken from this plant has thus far shown noth- 
ing definite except that at least a part of the 
divisions are mitotic. 
The most interesting thing made out in 
connection with the cell morphology is that 
first pointed out by Toumey for the almond 
gall, viz., the occurrence of more than one nucleus 
in a cell without any evidence of the beginnings 
of a cell-wall between them. Toumey figures 
2, 3, and 4 nuclei in a cell. The writer has seen 
two well-developed ones in cells of the rose gall. 
ANTIBODIES. 
This is almost a wholly unworked field. Fig. 29.* 
The writer has seen nothing corresponding 
to the self-limited infectious diseases of animals, or which indicates that plants can be 
preserved by vaccines. The subject is of extreme interest theoretically. Practically it is 
of less importance, owing to the great number of plants which would have to be inoculated 
and their slight value individually in comparison either with the labor involved or with 
the individual value of the higher animals. One attack does not confer immunity on any 
plant so far as known to the writer. But in this connection it should be understood that 
we know as yet very little of all that is to be known about this group of plant diseases, and 
*Fic. 290.—Tumor on sugar-beet produced by a Schizomycete plated from crown-gall of peach. Inoculated Mar. 
11, 1908. Photographed May 4, 1908. Nearly natural size. Five plants were inoculated and all contracted the 
disease. Previously the organism had been passed by the writer twice through peach-trees with production of galls. 
