525 



Azolla and Salvinia, General Remarks. 



The first stage of the two organs (ovula) observed in 

 Azolla, has presented them enclosed in an involucrum of a 

 very cucullate form, the point turned inwards so as to touch 

 the axis. They are sessile cellular bodies of a concave or 

 cup- shaped form, the cup (the young tegument) being occu- 

 pied by a protruding cellular body (the nucleus) ; one is rather 

 more advanced than the other. PI. CX1X. Fig. 1., 4. 



The second stage presented them of a more oblong form, 

 the protruding cellular body being more surrounded by the 

 cup, (PI. CXIX. Fig. II. V.) by which in the third it is 

 completely enclosed. PI. CXIX. fig. lVa. 



The fourth stage presented them as still more oblong, with 

 a tendency to an urceolar form. The once protruding nuc- 

 leus is now completely concealed, the cup having become ex- 

 tended beyond its apex into a short mammilla having a narrow 

 orifice (the foramen). Minute examination at this stage dis- 

 closes a tendency, at least in appearance, in the aforesaid 

 mammilla to be lobed, as though it had been produced, not 

 by one, but by about four component parts. The same 

 stage has generally presented moniliform filaments in opposi- 

 tion with the apex of one or both organs. (PI. CXIX. Fig. IV.) 

 These moniliform filaments are found within the involucrum 

 from the earliest period examined, but were not observed to 

 have any positive relations with the organs before this period. 

 They now plainly pass into the organs, and have therein soon- 

 er or later appeared to be resolved into their component 

 joints, which occupy the cavity existing between the once 

 protruding body and the foramen. (PI. CXX. Fig. II., PI. 

 CXXI. Fig. II., P1.*CXIX. Fig. II.) And this is so constant, 

 that even in cases where the moniliform filaments are not seen 

 in application with the foramen, or passing through it, the 

 space just particularised will found filled with their component 

 parts. PI. CXX. Fig. III., PI. CXXI. Fig. IV. 



Up to this time both the organs have presented a cellular 



