1900] DEVELOPMENT OF THE POLLEN GRAIN 83 
framework contracts, at first irregularly. Finally it becomes 
closely pressed together, or ‘balled up,” so that individual linin 
elements cannot well be distinguished, except where there are a 
few loose ends apparently serving for attachment to the nuclear 
membrane (fig. z). The nucleolus is usually embraced in this 
contracted mass on one side, so that it protrudes prominently. 
Even in this condition, one or more slight projections on the 
nucleolus may sometimes be seen on the side near the contracted 
mass. The interwoven linin substance takes a diffuse stain, In 
the general mass there are also globules of a deeper staining 
substance. The nucleus does not become spread out against the 
wall, as described in some cases;* but it is usually situated on 
the side of the contracted mass distant from the wall. The con- 
tracted mass is either in contact with the nuclear membrane, or 
connected with the latter by linin threads. 
During synapsis the cytoplasm becomes more loosely netted; 
and in Symplocarpus there is often an assemblage of kinoplasmic 
elements in that part of the cell which contains the greatest 
amount of protoplasm. These fibers are hardly so arranged as 
to be termed a cytoaster ; and their general position may be either 
radial or oblique to the wall. A considerable number of large, 
deeply - staining granules are distributed in the cytoplasm. 
Another change which seems to be dependent upon synapsis is 
noted in the smaller nucleolar-like bodies of the nucleus. As 
separate bodies, any of these which may have existed in the rest- 
ing condition disappear during synapsis, or they become closely 
adherent to the nucleolus and indistinguishable from the budded 
appearance of the nucleolus in the spirem, as mentioned later. 
Synapsis has been found at a definite stage in the sporogen- 
esis of many plants.2, The marked differences noted in the stages 
_ *SARGANT: The formation of the sexual nuclei in Zilium Martagon. 1. Oogen- 
esis. Ann. Bot. 1: 457. 1896. 
°Cf. a) Farmer: On spore formation and nuclear division in the Hepatice. 
Ann. Bot. g: 473, 481, 490. 1895. 
6) STRASBURGER: Theilungsvorgang des Zellkerne, figs. 3, 66. 
¢) CALKINs : Chromatin-reduction and tetrad-formation in pteridophytes. Bull. 
Torr. Bot. Club 24: fig. 37. 18 
@) SARGANT: 7. ¢., also, II, Spermatogenesis. Ann. Bot. 11: 187. 1897. 
