696 Sargant.—Recent Work on the Results 
time they leave the pollen-tube. In shape they are ovoid as 
in Endymion (Strasburger, 11 , pp. 298-301). 
On the other hand Nawaschin (8, p. 228, Fig. 1) has shown 
that the generative nuclei in the embryo-sac of Helianthus — 
and to a less marked degree those of Rudbeckia —are shaped 
like a corkscrew, and their appearance does strongly suggest 
that they possess the power of independent motion. 
From the sum of these observations we may conclude that 
possibly the generative nuclei in some species of Angiosperms 
may make their own way through the embryo-sac to the 
nuclei at which they aim, but that in others this passage is 
almost certainly effected by the streaming motion of the 
cytoplasm in the embryo-sac, which carries the nuclei pas¬ 
sively with it. If this be so, the power of automatic move¬ 
ment would seem to be an adaptive character, assumed or 
laid aside by the generative nuclei according to circumstances. 
These nuclei are indeed homologous with the nuclei contained 
in the spermatozoids of Vascular Cryptogams and Cycads, 
but they do not appear to be accompanied by any vestiges of 
the differentiated cytoplasmic structure characteristic of those 
bodies. 
If we call the generative nuclei of Helianthus , for example, 
spermatozoids or antherozoids, we imply that the differentiated 
cytoplasmic element in such structures is not essential. This 
amounts to re-defining the terms, a serious step to take in 
order to emphasize a phylogenetic theory which is, to say the 
least, very doubtful. If we extend either term to include such 
non-motile nuclei as those of Monotropa , and probably those 
of Endymion , Tulipa , and others, we further give up the 
character of automatic motion, and it is difficult to see what 
is retained to distinguish a spermatozoid from a male cell or 
even from a male generative nucleus. This applies equally to 
the spermatia of Florideae (Guignard, 4 , pp. 375-6 footnote). 
III. Homology of the Embryo-sac and its Contents. 
One of the greatest gaps in our knowledge of vegetable 
morphology lies in our ignorance of the pedigree of Angio- 
