SVKNSK l^OTANISK TiDSKRIFT. 1923. Bd. 17, H. 4. 



A PRELIMINARY NOTE ON THE CYTOLOGY OF 

 NICOTIANA SPECIES AND HYBRIDS. 



BY 



THOMAS HARPER GOODSPEED. 



For över fifteen years a collection of species and varieties ol 

 Nicotiana has hecn grown in the University of California Botanical 

 Garden and genetic investigations of a varicty of sorts have been 

 carried on, the results of which have been published in the Uni- 

 versity of California Publications in Botany, volumes 5 and 11 

 and elsewhere. 



To a preliminary list of chromosome numbers in Nicotiana al- 

 ready published there is little to be added at Ihis timc. Some 

 further examination has been made of N. alata, longiflora and 

 siiaueolens and the following amended fist of chromosome numbers 

 includes the results of these studies. 



X 9 — N. Langsdorffii. 

 x8, 9 or 10 — N. alata. 



X 1 — A^ longiflora. 



x 12 — N. sijloestris, glaiica, ghitinosa, paniciilata,acuminata. 



X 18 — A^ suaneolens. 



X 24 — N. Tabacum, riistica, Bigelovii, midicanlis. 



In fig. 1 are shown homotypic anaphases of alata, in b three 

 of the four plates with nine chromosomes in each and in a all 

 the four plates two of which are made up of eight chromosomes 

 and the other two of ten chromosomes. Failure of con]ugalion 

 in the case of one chromosome pair will account for this latter 

 condition. P. M. C. in this stage showing two anaphase plates 

 with nine and two plates with ten have been observed as well as 



