levine: somatic and reduction divisions in drosera 127 



Syringa rothomagensis and its parents 6*. vulgaris and 6*. persica. 

 He found that the reduction divisions in the hybrid were abnormal. 

 Invariably chromatin or chromosome-like bodies appear in the 

 cytoplasm during division stages. These bodies take the chroma- 

 tin stain and become invested with a nuclear membrane. The 

 origin of these bodies is not clear. Juel believes that these bodies 

 arise from the amitotic division of the nuclei of pollen mother- 

 cells which disintegrate. Juel holds that the sterility of pollen 

 is due to the abnormality of the tetrad division. Tischler in his 

 interesting papers ('05, '06, '08, '10) on the causes of the sterility 

 of pollen in hybrid plants finds that in Ribes Gordonianum the 

 chromosomes are irregularly distributed in the first division of 

 the pollen mother-cells so that more than two daughter nuclei 

 are formed. In sterile Bryonia hybrids and in three varieties 

 of Musa sapientum he described similar conditions. In the 

 former case he believes that the abnormality in the first and 

 second divisions of the pollen mother-cells is similar to that in 

 Hemerocallis fiilva (Juel, '97). In Potentilla similar conditions 

 appear, yet in both Bryonia and Potentilla normal pollen is also 

 found. It is of interest to note that In the three varieties of 

 banana. Dole, Radjah Slam, and Kladi, there are eight, sixteen 

 and twenty-four chromosomes respectively. 



Gates ('07) in a study of hybrids between Oenothera lata 

 and 0. Lamarckiana described and figured chromatic bodies in 

 the cytoplasm of the pollen mother-cells during division. He 

 observed the complete sterility of certain anthers of a flower and 

 associated this condition with the appearance of these bodies. 

 In a later paper ('14) Gates and Thomas reported their work on 

 Oenothera lata and 0. semilata. Here they found 1 5 chromosomes in 

 the somatic divisions and that while in the pollen mother-cell the 

 extra chromosome behaved differently — it most frequently was 

 left behind on the spindle. Gates believes that the union and 

 segregation of chromosomes tends to be in two numerically equal 

 groups. 



Geerts ('09, '11) in a cross between Oenothera lata and 0. gigas 

 found In the hybrid a condition similar to that observed by 

 Rosenberg in D. obovata. The male gametes have fourteen 

 chromosomes and the female gametes have seven chromosomes 

 and the hybrid twenty-one, In two sets, seven and fourteen. In 



