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AMERICAN JOURNAL OF BOTANY 
[Vol. io. 
one or more threads attached to them (fig. 21). As the daughter nuclei 
increase in size, one or more nucleolar bodies appear in connection with 
some of the chromosomes. In the resting stage of the nucleus the chromo¬ 
somes become somewhat more condensed, and there is usually but a single 
nucleolus present (figs. 22 A, 22 B). This resting stage appears to be of 
short duration. The chromosomes become more angular during the 
succeeding prophase stages and appear to be split about the time that they 
are drawn toward the equatorial plate; several of them are in contact with 
the nucleolus, which in turn becomes irregular and extended. In some 
cases the two spindles are arranged in the same plane, but more usually 
they are at right angles to each other. The further stages of division of 
the daughter nuclei appear to be like those of the heterotypic division. The 
tetrad or granddaughter nuclei show clearly the thirteen chromosomes 
scattered about in the nucleus (fig. 23). 
In the resting stage of the vegetative cells the chromatin occurs as definite 
chromatin-staining bodies; there is no conspicuous pairing of these bodies 
in this stage, but when the nucleus is undergoing the late prophase stages in 
division, the association of chromosomes of similar shape and size does 
become apparent (fig. 25), although they were never found joined together; 
this same condition of pairing was observed in the metaphase stage (fig. 24). 
In the megaspore-mother-cell nucleus, several prophase stages were 
observed including synapsis, but all presented the same phenomena as 
those observed in similar stages of the pollen mother cell. 
Discussion 
Cardiff in his work on Acer platanoides called attention to the chromatin 
in the resting nucleus of the mother cell as collected in small bodies at the 
periphery of the nucleus, but he did not consider their number. Although 
one cannot be entirely certain, yet I am convinced that the number corre¬ 
sponds to the number of chromosomes observed in the division stages^of 
the vegetative cells. These chromatin masses are doubtless a phase in the 
life history of the chromosomes, and correspond to the prochromosomes of 
Overton. In my earlier work on Acer negundo similar chromatin bodies 
were observed, but no attention was given to the number present; a re¬ 
examination of these stages as well as of later ones has led me to conclude 
that the phenomena of chromosome-formation in the two maples are 
essentially the same and that certain stages in the preceding work were 
misinterpreted. 
The bud-like structures on the nucleolus were noted by Cardiff and 
figured both by myself and by Mottier in Acer negundo. There is evidence 
that these break off from the nucleolus during the growth period of the cell, 
since occasionally one or more are found lying free in the nucleus; this fact 
may be determined in nuclei well stained with the triple stain, in which the 
nucleoius and these buds stain with the safranin and the chromatin bodies 
