Blackman and Welsford. — Fertilization in Lilium. 113 
to show that the pointed end moves first. Figs. 2 a and 2 c do certainly 
suggest very strongly a capacity for progression by creeping or some 
undulatory movement. Nawaschin has already pointed out the difficulty of 
accepting the view that two separate currents of cytoplasm take the nuclei 
as they lie close together and carry them in opposite directions. Some 
chemotactic relation between the approaching nuclei would seem to be 
a necessary assumption, for, as Nawaschin points out, it is only the male 
nuclei which are so carried — other granular bodies which accompany them 
into the embryo-sac remain behind. In Fritillaria , and perhaps in Lilitim 
though we were unable to elucidate this point, the contents of the pollen- 
tube pass, not into the cytoplasm of the embryo-sac, but into a space 
between the cells of the egg-apparatus, above, and the cytoplasm of the 
polar nuclei, below. 
It is to be noted that even at the earliest stage in which the male 
nuclei have been observed in the embryo-sac there is a distinct difference 
in their size (Fig. 5), the forward ones being narrower and smaller. As the 
nucleus in contact with the female cell is generally smaller than the one in 
contact with the polar nuclei it is probably the one which lies towards the 
apex of the pollen-tube which fertilizes the egg-cell (compare Figs. 1 
and 5). 
In the contents of the pollen-tube after their entry into the embryo-sac 
two very deeply staining bodies are to be seen (Figs. 5 and 6) ; these are of 
doubtful nature and correspond to the X-Korper of Nawaschin. Also in 
Fig. 1 there is a band-like structure which stains deeply with safranin and 
lies just below the female cell and almost in contact with the lower male 
nucleus. There are also three other fragments of a similar nature lying 
close by. Are these possibly the remains of an abortive blepharoplast 
or cilia-bearing band ? 
The material was fixed in Flemming’s strong fluid, and as the 
sections were mostly thick for convenience of examination, they were 
stained deeply in safranin, washed out with alcohol, and then treated with 
Lichtgriin dissolved in clove oil. By this means a very transparent stain is 
obtained, enabling one to examine with ease sections so thick (20 jutor more) 
that they would be completely obscured by the use of gentian-violet. 
EXPLANATION OF PLATE XII. 
Illustrating Professor Blackman’s and Miss Welsford’s paper on Fertilization in Lilium. 
Fig. 1 . Section of the ovule of Lilium Martagon at time of fertilization. The two male vermiform 
nuclei are well seen, also the egg and the synergid. A deeply staining band and other bodies are 
to be seen below the female nucleus, x 680. 
I 
