MARSILIA VESTITA. I95 



The grains of starch are especially large and conspicuous. 

 The wall of the spore shows much the same structure as 

 that of the microspore, but the peculiarities are more 

 marked. The epispore is especially well developed and 

 differs mainly from that of the microspore in the prisms 

 of which it is composed being in close contact and 

 appearing in surface view as polygonal areas in close 

 apposition. Outside' of the epispore proper the struc- 

 tureless mucilaginous outer epispore forms a more or 

 less conspicuous layer. It stains deeply and is especially 

 developed toward the upper part of the spore. This 

 layer is not shown in figures i and 12. 



A very full account of the structure of the cell, as well 

 as their development, is given by Strasburger.* 



The development of the female prothallium is some- 

 what slower than that of the male, and ordinarily takes 

 fifteen to twenty hours for its completion, although if the 

 temperature is high it may be completed in somewhat less 

 time. 



The first sign of germination is an increase in the size 

 of the hemispherical mass of protoplasm at the apex of 

 the spore, and the boundary between it and the body of 

 the spore becomes somewhat less decided (pi. iv, fig. 2). 

 At the same time the nucleus becomes more nearly glo- 

 bular, and its contents, which in the ungerminated spore 

 appear almost uniformly granular, become somewhat dif- 

 ferent. The granules become larger, and some of them 

 stain more deeply, showing them to be chromatin bodies 

 (pi. IV, fig. 4). At no time, however, is the amount of 

 chromatin large. The first division was not observed in 

 any spores that had been in water for less than two hours, 

 and probably very seldom occurs sooner than this. Usually, 



*Strasburger. Uber den Bau nnd Wachsthum der Zellhaiite, pp. 123-133. 



