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 Cichoriew 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 cytological point of view, the specimens 
which were used; but I myself was unable to do this, not being 
acquainted with the cytological 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”). 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 A. flagellare) the tetraédric divisions with reduced num- 
bers of chromosomes are carried out. Some of the mothercells of the 
