110 oe BOTANICAL GAZETTE [FEBRUARY 
probably disappear at the end of the first mitosis. These bodies are 
also found in the O. Lamarckiana hybrid, in which they doubtless 
have the same origin. They probably represent discarded chromo- 
somes, and this is perhaps a means of lessening the number of chromo- 
somes in certain germ cells of the species. Some mother cells do not 
contain them. In such cells the (sporophyte) count of chromosomes 
in O. lata is fourteen and in the O. Lamarckiana hybrid probably 
twenty. 
4. The occurrence of extra nuclei formed by chromosomes left 
behind in the cytoplasm in the tetrad divisions of the hybrid O. /ata, 
as well as in a number of other hybrids recently described, puts under 
suspicion the purity of any other plant, such as Hemerocallis julva, 
in which such extra nuclei are known to occur. 
5. The inference seems justifiable that the mutations of O. 
Lamarckiana arise during the reduction divisions and that pollen 
grains which will give rise to mutants differ in their potentialities and 
probably also in chromatin morphology from the ordinary pollen 
grains of the plant. 
These facts lead to the conclusion that a cytological basis may 
be found for the phenomena of mutation as observed in the 
Oenotheras. 
THE UNIVERSITY OF CHICAGO 
LITERATURE CITED 
I. ALLEN, C. E., Nuclear division in the pollen mother cells of Lilium canadense. 
Ann. Bot. 19: 189-258. pls. 6-9. 1905. 
. Bartey, L. H., Cyclopedia of American horticulture. 4 vols. Macmillan 
and Co. —— York. 
3- Breer, Rupotr, On the development of the pollen grains ge anther of some 
Onagraceae. Beih. Bot. Centralbl. 19! : 286-313. pls 3-5. 1905. 
4. Cannon, W. A., Studies in plant hybrids: The emai of hybrid 
peas. Bull. Torr. Bot. Club 30:519-543. pls. 17-19. 1903. 
, Studies in plant hybrids: The Sean See of hybrid cotton. 
rr 133-172. pls.7-8. 1 
CarvirF, IrA D., A study of spndipats and reduction. Idem 33:271-306- 
pls. 12-15. ek 
6a. Cook, O. F., and Swincte, W. T., Evolution of cellular structures. Dept. 
Agric. Seen of Plant Seduuiry. Bull. 81. pp. 26. pl. 1. 1905. 
N 
” 
e 
