368 TRANSACTIONS AND PROCEEDINGS OF [Sess. lvi. 



base. We find now at the time of the formation of the 

 synergidse the retrogressive changes of the periblem-cells 

 restricted to the apical portion of the ovule, and it is quite 

 conceivable that by the breaking down of cells, food-materials 

 will be set free which are directly available to the cells lying 

 in the apical portion of the embryo-sac. Glancing at figs. 

 24 and 25 a we see that the two synergidise {syn) occupy the 

 most apical position in the sac, in other words, that they 

 are the two cells next the supply of food, and it is natural 

 that as the embryo-sac elongates, the nuclei and the pro- 

 toplasm of the two synergidse should continue to lie in as 

 close a connection as possible with the apical part of the sac, 

 i.e., the supply of food. To accomplish this the cells must 

 keep step with the elongation of the sac, and hence a vacuole 

 is formed in the basal end of each cell ; its function being to 

 increase the tension within the cell and to allow the nucleus 

 and the bulk of the protoplasm to recede from the basal un- 

 profitable end to the micropylar end where supply is 

 plentiful. 



The egg-cell is usually placed to one side of the two 

 synergida?, and at a somewhat lower plane, t.r., further removed 

 from the region in which nucellar cells are degenerating. 

 If then my contention of food-material passing into the 

 micropylar end of the embryo-sac be correct, the egg-cell 

 will not be supplied with nourisliment to the same degree 

 as the two synergidse ; and the sister-cell of the ovum, the 

 primordial cell, which, as we have seen above, lies below 

 the synergidaj and the ovum, will be as regards nutriment, 

 the most unfavourably placed cell in the micropylar half of 

 the embryo-sac. The latter cell placed under these disad- 

 vantages begins to look out for a new source of food, its 

 protoplasm streams over the inner aspect of the embryo-sac 

 and ultimately comes in contact with the protoplasm of the 

 antipodal micropylar cell (figs. 25-31). The latter, however, 

 is in the same distress as its neighbour, as I judge from the 

 facts, that its protoplasm also is wandering over the inner 

 aspect of the embryo-sac evidently in search of food, and 

 that as in fig. 27 a branch {I) has even been sent out, 

 between the antipodes and the sac-wall, to reach the plerome- 

 elements which are the conductors of food-material to the 

 ovule. 



