AZOLLA AND SALVINIA. 



533 



out using pressure ; they are of unequal size, and of a yel- 

 lowish brown tinge. Though previously empty they now 

 contain grumous coagula cohering to the sides ; the larger 

 present in addition granules. 



The trifacial cells often appear grouped. No oil escapes 

 on pressure, or I should have attributed the superficial cellu- 

 lar appearance (it is altogether like nascent cellular tissue, 

 and its precursion by grume is like this too) to the same cause 

 as the apparent cellularity of the incrustation. In some, 

 abortive trifacials may be seen. 



The changes that take place in the larger capsules from 

 the same period, chiefly affect the central sac, which, when 

 detached, will be found to present a similar, but relatively 

 smaller trifacial surface (PI. CXXVI. Fig. I.,c.) ; at this pe- 

 riod this sac is about equal in size to the trifacial cells, visi- 

 ble in the circumference of the grume. But it never has pre- 

 sented to me their empty appearance. PI. CXXVI. Fig. II. ,3. 

 PI. CXXVI. Fig. I.,5, I., 6. 



The next period presented this central sac a good deal en- 

 larged, still apparently isolated ; it is surrounded by a much 

 thinner mass of grume, which from the frequent absence of 

 the radiating* lines, often appears free of attachments. The 

 space between this grume and the inner wall of the secondary 

 capsule is more or less occupied by free trifacial cells (PI. 

 CXXVI. Fig. I., 3a, 5, 7.) The grume itself on escaping 

 from the capsule will be found to present the trifacial cells, 

 and larger cells, {parent cells) exhibiting indications of divi- 

 sion. PI. CXXVI. Fig. I., 9. 



The central sac continues to increase : the grume sur- 

 rounding it to diminish, until it is reduced to a thin coating. 

 Generally about this period the sac has appeared to be at- 

 tached to the apex of the cavity of the secondary capsule by 



* But I have remarked that while the trifacial cells are being imbed- 

 ded, the trifacial surface is turned to the peryphery. Can this have any 

 reference to germination ? 



