— 226 — 



published by us in a short note in this journal. The main point 

 was: all the examined species of Hieracium produced fullgrown 

 fruits after castration and, consequently, they behave like the Taraxaca 

 which Raunkiær has proved to be apogamic, probably parthe- 

 nogenetic; on the other hand other genera (21) af Cichorieœ do not 

 bear fruits after castration. 



Upon this interesting beginning I continued the investigations, 

 and soon it appeared, that the case was much more complicated, 

 for the same individuals are able to produce fruits (with power of 

 germination) after castration, and also to produce fruits after fer- 

 tilisation with pollen of another species, thus originating hybrids. 

 Two short notes on the question have been published by me in 

 "Berichte d. Deutsch, bot. Gesellsch.", vol. XXII, 1904. It 

 was because I happened to find in our Botanical Garden a species, 

 Hieracium excellens, which is purely female (the anthers being 

 empty), that I succeeded in constating this perplexing fact. 



Now it naturally seemed necessary to go more into detail 

 with the experiments and mainly to base them on this female 

 species. Moreover it became desirable to extend the experiments 

 to many more species of the genus, especially to examine represen- 

 tatives of all the sections of it. — In the present paper I give a 

 report of all my experiments carried out until now, but it follows 

 as a matter of course that the work will be continued in future 

 years. 



At an early stage of my studies I felt how necessary it would 

 be to examine, from a cytologicai point of view, the specimens 

 which were used; but I myself was unable to do this, not being 

 acquainted with the cytologicai methods and technique. I. therefore 

 asked Dr. O.Rosenberg of Stockholm, whose cytological researches 

 (in Drosera etc.) are well known, to help me, and I was very 

 glad that he accepted my proposal. I take here the opportunity 

 to offer him my best thanks. How valuable his help has been 

 and how many new and unexpected facts he has brought to light, 

 will be evident from his accompanying paper 1 ). I am sure that 

 I could not have found a better collaborator. 



1 ) Dr. Rosenberg has published a preliminary report on some of his results 

 in Ber. Deutsch. Bot. Gesellsch., vol XXIV, No. 3 (April 1906). In this 

 paper he resumes his studies as follows: "In most of the ovules of H. 

 excellens (and of E. flagellare) the tetraëdric divisions with reduced num- 

 bers of chromosomes are carried out. Some of the mothercells of the 



