82 Allgemeines. 



feldii fluctuate, having sometimes a climax at 13, sometimes at 21 and 

 sometimes two climaxes at 13 and 21 each. Countings of bracts of 

 other Compositae are shortly mentioned. 



4. The most important part of the paper is the pointing 

 out of the fact that the DandeUon bears fruit without 

 fecundation. In 1898 C. H. Osten feld has shortly 

 mentioned, that he had discovered female plants of T. vulgare 

 among the hermaphrodite ones and that T. paludosum had been 

 found female only and probably must be apogamic. Now the 

 author crossed the female T. vulgare with T. Gelertll hoping 

 to obtain an intermediate form (T. Intermedium). The result 

 was an abundant fructification, but the flowering offspring 

 consisted solely of female plants exactly like the mother 

 plants without any trace of T. Gelertil. Female plants of 

 T. vulgare were then placed in such a manner that 

 fecundation from foreign plants was prevented; they produ- 

 ced nevertheless many and full-grown fruits which again gave 

 rise to a new female generation. Consequently these female 

 plants constitute a distinct species, T. Ostenfeldii, which bears 

 fruit without fecundation. Experiments with T. paludosum, both 

 Crossing and Isolation, gave a similar result. 



To prevent all sources of error the author made the follo- 

 wing simple and ingenious experiment: he cut off with a 

 razor the upper half of the un-opened f lo wer-head s; 

 by this Operation the greater part of the corollas, the anthers and 

 the Stigmas were removed and only the basal part of the corolla- 

 tubes, the filaments and the styles were left on the ovaries. 

 This violent Operation succeeded ; the remaining fragments of 

 corolla, filaments and style enlarged and the ovaries deve- 

 loped into fullgrown achenes, which differed from the 

 normal ones only in the short-cut pappus. After that the 

 production of seed without fecundation was an incontestable 

 fact in the two mentioned female species. 



Starting from that, he began his experiments with the 

 hermaphrodite species. He had observed that the offspring of 

 a plant was all of a remarkably homogenous aspect while one 

 would suppose that the dandelion, as one of the most frequently 

 visited insect-flowers, would often be fecundated by foreign 

 pollen and that the offspring should consequently vary to a 

 considerable extent. By cutting off the upper part of the 

 flowers, in the manner mentioned above, he obtained here also a 

 plentiful crop of full-grown achenes, and so it was proved that, 

 the hermaphrodite form also in spite of its producing lots of 

 pollen, bears fruits without fecundation. The same was found 

 to be the case with T. vulgare, T. Gelertll and T. intermedium, 

 further T. obovatum (Willd.) DC. from Southern Europe 

 and T. glaucanthum (Ledeb.) DC. from Pamir. The purely 

 female species T. speclosum and T. declplens from Denmark 

 and T. croceum Dahlstedt from Greenland and from 

 Norway produced fruit without fecundation. 



