230 On Azolla and Salvinia. 



cells of the surface of the organ has increased, so has the 

 browning of the apex, which still often presents traces of ad- 

 hering moniliform filaments. Both organs also exhibit distinct 

 vessels prolonged from the vessels of the axis into their bases. 

 (PL 15./. 12. 13. 14.) 



The next stage presents nothing particular in the appear- 

 ance of the organ, or the enclosed moniliform filaments. The 

 nucleus however, presents about its centre, in lieu of the 

 grumous disc transparent in the centre, a well defined small 

 yellow sac, and between it and the apex of the nucleus, 

 a grumous mass is seen presenting what appear to be several 

 small points of condensation. (PL 16./. 4. 5.) Somewhat later 

 the organ having increased a little in size, the yellow sac is 

 found to be as it were capped by the grumous mass, (PL 16. 

 /. 6. 9.) which presents shortly after indications of division 

 (lobes) on its surface. (PL 16./. 7. 8.) 



The space between the apex of the nucleus and the now 

 very brown apex of the organ, still presents the dislocated 

 joints, which now form a column of communication between 

 the foramen and the nucleus (PL 16./. 6.) ; parts of the moni- 

 liform filaments may often also be found adhering to the fora- 

 men itself. 



The lobes mentioned as appearing in the capping grume 

 continuing to be developed, encroach upwards on the nucleus 

 (PL 16./. 7.) ; and the yellow sac, which, as the lobes increase 

 in consistency, appears more and more distinctly pendulous 

 from their mass, becomes gradually covered with an incrus- 

 tation. The joints of the moniliform bodies which previously 

 could be easily squeezed out through the foramen disappear 

 about this period. (PL 16./. 7.) 



When fully developed the organ presents scarcely if any 

 change of form : most of the cells of the surface are gorged 

 with pink fluid ; the apex is distinctly brown. The cavity 

 of the organ is occupied by a complex body, consisting of 

 two dissimilar parts ; the upper, which forms rather more 



