6 ARKIV FÖR BOTANIK. BAND 17. N:0 11. 



Of other parthenocarpic species little is known. Partheno 

 carpic fruits are, however, reported from several steril« 

 hybrids — forms, consequently, really known as hybrid: 

 (cf. Ernst 1918) — in which a close relation between cros 

 sing and parthenocarpy is obvious. On the other hand 

 EwERT (1910) succeeded in producing seedless fruits of i?i6e 

 grossularia by means of several external influences such a 

 breaking the twigs or removing all the flowers but one whicl 

 was thereupon castrated. Recently Wölfert (1920) ha 

 arrived at similar results with Solanum, Impatiens and others 

 In these cases, parthenocarpy is obviously an outcome o 

 abundant nourishment of the flowers. In the hybrids, again 

 it might be regarded as an outcome of certain stimuli, which 

 however, lead to the same result, viz. abundant nourishmen 

 of the flowers. Parthenocarpy is obviously an effect of quit 

 special metabolic circumstances which are sometimes brough 

 about by crossing, sometimes through some other inter 

 relations between genotypical constitution and external fac 

 tors. Inter alia, the tropical climate is probably such i 

 factor, favourable to parthenocarpic development. Also th' 

 degeneration of the embryo-sacs and embryos in seedless fruit; 

 may certainly be brought about in more than one way. L 

 any case, parthenocarpy cannot be regarded as an unquesi 

 tionable indication of previous crossings. 



Botanical Institute, University of Stockholm, Septembe 

 1921. 



