Cytological instability in tumors of Picea glauca.

Smear preparations of cells taken from primary explants of normal and adjacent tumor wood of Picea glauca showed completely regular mitotic behavior in the normal cells, with the great majority of cells diploid (22 chromosomes), a few tetraploid, but almost none aneuploid. Tumor tissue was extremely unstable, with numbers ranging from 3 to more than 70, with a high proportion of aneuploids but otherwise normal-appearing mitoses. The relation of this mitotic instability to other data on these tumors is pointed out.