o, HEILBORN, CYTOLOGICAL STUDIES ON CARICA. 15 



nvestigated. The reduction division is normal in C. Papaya, 

 \ candamarcensis and perhaps also in C. chrysopeiala. 



4) In C. pentagona both normal and aberrant reduction 

 pindles are found, the latter showing an almost total failure 

 f chromosome conjugation. Ovules are sometimes found 

 nth two mother-cells, one of which shows complete, the 

 ther one defective conjugation. It is also possible that the 

 onjugation is different in different individuals. Mother-cells 

 nth defective chromosome conjugation give rise to diploid 

 DF almost diploid) embryo-sacs which may perhaps be 

 apable of apomictical development. 



5) C. chrysopeiala and C. pentagona are dioecious and 

 lale individuals are lacking. Both species are almost to- 

 ally parthenocarpic, only very few seeds being found in 

 ach fruit. It is untertain whether these seeds are of apo- 

 lictical or of hybrid origin. In the latter case G. canda- 

 larcensis must be the male parent. 



6) According to the theory of Ernst (1918) this parthe- 

 locarpy should be regarded as an outcome of previous cros- 

 ing. It is, however, stated that no decisive proof can be 

 ound by means of taxonomical and cytological studies for 

 r against such an assumption. 



Botanical Institute, University of Stockholm, 

 September 1921. 



