288 REPORT OF THE CONFERENCE ON GENETICS. 
By crossing H. Pilosella with H. aurantiacum an intermediate hybrid 
appeared. This hybrid has a very slight power to give fruits ; after castra- 
tion all the fruits are empty, but in the heads which were neither castrated 
nor isolated some few full fruits occurred. These fruits have germinated, 
and the offspring had begun to flower when I left Copenhagen a few days 
ago. Most of these plants are different from their mother, the primary 
hybrid; a few are somewhat like it, others are nearer to H. Pilosella, 
others again are pure H. Pilosella, and a single plant differs from both its 
mother and its grandparents. As the heads have not been isolated, it is 
probable that this variation is caused by cross-fertilisation with H. Pilosella 
or with other species (the latter is probable as to the last-mentioned 
individual); but, on the other hand, the pure H. Pilosella argues 
Mendelian segregation. It is indeed necessary to repeat the experiments 
and isolate again, as at present it is quite impossible to give a sufficient 
explanation. 
It will be evident from the report here given that the investigations 
are only in their beginning. But the whole problem of the heterogeneity 
of the fructification phenomena in the genus is of such interest that I 
hope it justifies this short communication.* 
The genera Hieracium and Taraxacum are usually considered as the 
most developed and youngest members of the Cichorie, which group 
again is placed as the highest and youngest of the Composite—the 
youngest and largest order of Flowering Plants. And, seen from that 
point, the abnormity or degeneration with regard to fertilisation in the 
two genera is not least interesting. 
* A fuller report of the experiments, illustrated with coloured drawings of the 
hybrids, is published in English in Botanisk Tidsskrift, vol. xxvii. 1906, pp. 225-248. 
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