Fertilisation , Apogamy and Parthenogenesis. 155 
an embryo from an apparently normal egg-cell has been observed 
in Antennaria alpina, in several species of Alcliemilla, in Thalictrum 
purpurascens and Taraxacum officinale. It appears, however, that 
in all these forms the number of chromosomes is not reduced 
in the megaspore-mother-cell, and Juel has observed in Antennaria 
and later in Taraxacum 1 that there is no tetrad division but the 
embryo-sac mother-cell only divides once; Overton 2 has also observed 
in Thalictrum the absence of the second division. In these cases 
of “parthenogenesis” and in those of animals we have thus the 
special reproductive cells (gonotokonts of Lotsy ), 3 which usually form 
a tetrad of cells and undergo a reducing division, dividing only 
once and showing no reduction of chromosomes. 
That the term parthenogenesis is as unsuitable in these 
cases as in those of animals is clear when it is considered 
that the “ gametophyte ” and the “ egg” have the double number of 
chromosomes from the beginning, so that in the absence of 
reduction fertilisation is quite unnecessary. The gametophyte here 
provides an interesting case of a tissue which it is difficult to place in 
the category either of gametophyte or sporophyte for it has the 
general morphological features of the one and the cytological 
characters of the other. 
It is very evident that in these peculiar cases amongst animals 
and plants we have reached the lowest stage of reduction in con¬ 
nection with fertilisation. The mingling of different characters, 
the stimulus to development, and the doubling of the number of 
chromosomes have all disappeared; and from the standpoint of 
cytology the process is reduced to one of mere somatic or sporophytic 
budding. That it is a stage in the reduction of fertilisation is shown 
by the fact that the process still continues along the lines of sexual 
reproduction, and involves the formation of “ gametophyte ” and 
“ egg.” Also, through such a case as the union of sister gametes in 
Artemia, the special types of fertilisation to be observed in the 
aecidium of Phragmidium, and the types of fertilisation to be observed 
in many fungi, these processes of “ budding ” may be linked on to 
normal exogamous fertilisation. In fact the cell which develops the 
embryo may be looked upon as the result of a theoretical fertilisa 
tion, i.e. as the product of the union of the sister-cells which should 
have been formed (and are formed in Artemia) from the cell which 
1 Arsk. for Bot. II. (1904) No. 4. 
2 Her. d. Deutsch. Bot. Ges. XXII. (1904), p. 274. 
3 Flora XCIII (1904), p. 65. 
