| 1898] LIFE HISTORY OF THE PONTEDERIACEA 333 
fp. 52 and 53). The antipodals here also are ephemeral, 
becoming very indistinct at the time of fertilization and soon 
iter vanishing altogether. 
The development of the microsporangia and microspores 
presents no unusual phenomena. As in Eichhornia the layer of 
alls outside the tapetum disintegrates before the latter and the 
tayetal cells are always uninucleate. Figs. 57-65 represent 
_ ‘Mages in the division of the mother cells and, growth of the 
microspores. Neither the generative nor the tube nucleus 
txhibits any of the abnormalities observed in Eichhornia. 
_ The pollen tubes in their growth through the style are 
_‘onducted along three canals which are each lined with a 
single layer of glandular cells (fig. 55). This layer is con- 
tinued to the micropyle (fig. 56). The pollen tube entering 
‘the embryo sac was seen in several cases always passing between 
} thesynergids, one of which it destroys. Vestiges of the remaining 
_ Sergid are still in view when the embryo has grown to such a 
: we as in figs. 67 and 68. Apparently the pollen tube brings in 
Wo nuclei and its swollen end reaches almost, or quite, to the 
“phere nucleus before these are set free (fig. 54). 
‘ A few Stages of the young embryo are shown in figs. 66-71. 
2 Statement made in text-books that the roots of Pontederia 
: " dermatogen and hence no true epidermis applies only 
ty roots. In the young embryo (see jigs. 7, 71) 
: atts atogen is regularly cut off, and this in older embryos 1s 
om “ous with the calyptrogen. 
, attempt was made to study the cytology of Pontederia 
Sy T than to determine the number of chromosomes, which is 
bi. the pollen mother cell, and fifteen or sixteen in the 
> of the Sporophyte tissue. 
at er ke ines i ies a) ce eee 
HETERANTHERA GRAMINIS. 
- few tipe flowers of this species were sectioned and 
Rents and In: general appearance the ovule, with its . 
aad lh sac, bears a striking resemblance to those o 
. '@and Eichhornia. The synergids are longer and more 
