566 7 row. — On Fertilization in the Saprolegnieae. 
bear witness to the existence of fertilization in this most interesting group 
of Fungi. I venture to predict that the Saprolegnieae will soon furnish 
many more examples of typically sexual species. 
Summary of the Cytology in Achlya De B ary ana. 
1. The nuclei in the oogonia and antheridia all undergo a first mitosis, 
the number of chromosomes being apparently eight. 
2. Some of the daughter-nuclei in both oogonia and antheridia undergo 
a second mitosis in which the number of chromosomes is apparently 
reduced to four. 
3. Centrosomes and astrospheres are developed in the second mitosis 
in the oogonia, but have not yet been observed in the antheridia. 
4. The supernumerary nuclei in the oogonium undergo degeneration 
and absorption by the ooplasm. There are no nuclear fusions. The 
process of degeneration is virtually completed when ‘balling’ begins. 
5. The supernumerary nuclei in the antheridia and fertilization-tubes 
degenerate much more slowly than those in the oogonia. 
6. The ‘origins’ and oospheres are uninucleate. Each nucleus is 
associated with a well-developed centrosome and astrosphere, and an 
ovocentrum. 
7. In fertilization, an open communication is set up between the fertili- 
zation-tube and the oosphere, and a single male nucleus accompanied with 
a gonoplasm passes out of the fertilization-tube into the oosphere. 
8. The sperm-nucleus acquires, in the oospore, a centrosome and 
astrosphere, and as it moves towards the oosphere-nucleus, the centrosome 
and astrosphere are directed outwards. There is no rotation of the axis of 
the sperm-nucleus as in animal eggs. 
9. The fusion of the gameto-nuclei does not take place until centro- 
somes, astrospheres, and ovocentra have disappeared. The male centro- 
some does not seem to have any special significance in the act of fusion or 
of the subsequent mitosis. Boveri’s theory of fertilization does not seem 
applicable to plants. 
Literature. 
The following list includes the most important books and papers relating to the subject of this 
communication which have appeared in recent years. They have all been consulted directly. Very 
complete bibliographies will be found in many of them. 
Belajeff, W. (’98) : Ueber die Cilienbildner in den spermatogenen Zellen. Ber. der Deut. bot. 
Ges., Band xvi. 
(’99) : Ueber die Centrosomen in den spermatogenen Zellen. Ber. der Deut. bot. Ges., 
