14 ARKIV FÖR BOTANIK. BAND 17. N:0 12. 



fore, little reason to make any further comment on Ernst'i 

 theory. 



The embryology of C. candamarcensis agrees in all respecti 

 with the general scheme, outlined above for this genus. Th« 

 reduction division in the pollen mother-cells is quite norma 

 (Fig. 16). Pollen-tubes are often found. 



The same development is also found in C. Papaya 

 which, however, is somewhat surprising, the embryology o 

 that species having been studied by other investigators wit! 

 other results. According to Usteri (1907) and Kratzef 

 (1918) tetrads are found with three or four cells, of whicl 

 one developes into the embryo-sac. Usteri's data are rathe: 

 vague but Kratzer's seem to be accurate, for which reasor 

 it may be inferred that different races of papaya behave ir 

 a different manner. Moreover Kratzer reports norma 

 embryo-sacs, whereas Usteri says that antipodals are de 

 veloped but seldom. Pollen-tubes could not be found b} 

 Usteri in his material, but probably the ovules investigatft 

 were too young. I have seen them several times, ashasals( 

 Kratzer. The reduction division in the pollen mother-cell; 

 is normal and I have also seen a quite normal diakinesis ii 

 an embryo-sac mother-cell (Fig. 11). Hence Usteri's assump 

 tion that the seeds of papaya develop parthenogenetically i: 

 erroneous, especially as his own attempts to prove the par 

 thenogenesis experimentally were not successful. On tht 

 other hand, it is certain that parthenocarpy occurs in thi; 

 species too, as stated by Usteri and Kratzer, though i' 

 must be a rare event. I myself have never seen any seedless 

 fruits of papaya. < 



Su miliary. 



1) Two Ecuadorian species of Carica with edible fruitf 

 — C. chrysopeiala and C. pentagona — are described as ne« 

 to science. Notes are also made on the morphology anc 

 systematic position of C. candamarcensis Hook. 



2) The embryo-sac of these species and of C. Papayc 

 is described as being of Liliu7n-type, though only with t 

 nuclei. Antipodals are lacking. 



3) The somatic chromosome number is 18 in all speciee 



