184 Ikeno . — On Hybridization of some Species of Salix. II. 
nervis , perhaps hybrids, have been produced, but since they perished before 
flowering they are not enumerated in the table. 
From the results just enunciated we now can have no reason to 
doubt the production of multinervis progeny from multinervis mother 
without the action of multinervis pollen. 
It is well known that sometimes in some Salix species a few male 
flowers are produced on the female catkin, or even a few flowers become 
hermaphrodite. One might perhaps think that the production of multi - 
nervis progeny in our case might be due to such abnormalities which have 
escaped my attention. I have looked for them in our midtinervis trees 
carefully and repeatedly : it may be remarked in this respect that I have 
never met with even traces of such in our trees. 
When my former paper was published the fact whether or no the 
multinervis progeny under discussion will breed true in later generations 
was not yet decided, though this seems to me to be highly probable. 
I pollinated in 1920 two such multinervis progeny (from Nos. 26 and 
29 in Table I) by pollen taken from a multinervis male plant, and got 
a certain number of progeny. The latter were multinervis without excep- 
tion, so that my supposition that they will breed true has been fully 
confirmed. 
The next question will be, How are the multinervis progeny produced, 
without the action of multinervis pollen ? My conclusion in my former paper 
was that it may be ascribed neither to parthenogenesis nor to development 
of nucellar cells, but to so-called pseudogamous development of oospheres 
due to the stimulus of foreign pollen ( 1 . c., pp. 51-4). Some doubt, 
however, arose in my mind in 1919 about this conclusion. Mr. S. Nohara, 
then assistant in my laboratory, covered a number of young catkins of 
a tree cultivated in our botanical garden, and very similar to multinervis } 
with paper-bags for a certain purpose, and left them in this condition for a 
certain lapse of time, perhaps about two months. On opening them he was 
struck by the fact that some catkins had produced a few fruits. He notified 
me of the fact. I placed some seeds thus obtained upon a moist filter- 
paper within a Petri dish : some of them were so weak that they refused 
to germinate, but others germinated very well. Still others were sown 
in a seed-pan and came to germination. 2 From all these facts there 
will be no doubt about the occurrence of the ‘ apomictic 5 development 
without any pollination in this case, to use the word introduced by the 
German botanist Winkler. 3 
1 It may be a variety of multinervis ; it is chiefly distinguished from the latter by its smaller 
catkins. 
2 Plants derived from this germination are now cultivated in our garden. So far as we can 
judge by their leaves they are quite similar to their parent ; one of them has already borne female 
catkins, and proved itself to be perfectly similar to its parent. 
3 Parthenogenesis und Apogamie im Pflanzenreiche, Jena, 1908, pp. 8 ff. 
