ANGIOSPERMS. 
such as Allionia and Delphinium, they are very large and well-developed. In the 
Grammeae, Fischer has found that they divide and give rise to a considerable mass 
of cells, a fact which Strasburger has ascertained with regard to Ornithogalum, 
though here it is exceptional. In some instances the two polar nuclei meet, not 
in the centre, but towards the upper end of the embryo-sac; in this case the 
upper nucleus is stationary, and the lower nucleus has to travel nearly the whole 
length of the embryo-sac. This occurs, according to Fischer, in Elodea and in 
many Gramineae, and apparently also in Allium fistulosum. The coalescence of the 
two polar nuclei usually takes place before fertilisation, but in Alisma and in Allium 
fistulosum it does not take place until the pollen-tube has reached the embryo-sac 
or even until fertilisation has been actually effected. 
As regards the fate and the function of these various cells which are formed in 
the embryo-sac, the oosphere is the one which undergoes fertiHsation and developes 
into the embryo, the others being transitory structures. The synergidae appear to 
Fig. y)<).~Funkia cordata ; A apex of the enibryo-sac e, covered with a layer of cells belonging to the nucellus KK,x o\\& 
of the synergidag, o the oosphere with its nucleus ; B, C oospore before, D, E after the first division ; F the spherical suspensor 
with the two-celled rudimentary embryo (X Soo), 
cause the disintegration and in some cases at least the absorption of that part of the 
wall of the embryo-sac with which they are in contact, and besides this, they have 
a further function in the process of fertilisation to which reference is made below. 
In some cases {Crocus vernus, Torenia asiatica, Smiialum alburn^ their pointed ends 
become covered with a cap of a homogeneous substance which gives the reactions 
of cellulose : by this means they replace that part of the wall of the embryo-sac 
of which they have caused the absorption. After fertilisation the synergidae undergo 
absorption. In many cases the antipodal cells soon undergo absorption, but in 
some they persist, and may be seen at the base of the endosperm in the fertilised 
ovule. 
We will now proceed to discuss these phenomena from a morphological point 
of view. We have seen above that the cell which developes into the embryo-sac is 
the equivalent of one of the mother-cells of the spores in the sporangium of a Vas- 
cular Cryptogam, and to this we may add that it is equivalent to one of the mother- 
cells of the pollen in the pollen-sac of the stamen. With this as the basis of their 
