GENERAL REMARKS. 267 



should occur in the organs as in the branches, viz. that ex- 

 ternal tubes should not be developed. 



The trifacial cells were once seen in the female of Chara 

 furcata. In Chara there is the strictest conformity in both 

 sexis, with the structure of the axis. 



6. In Pilularia globulifera, it would appear that the first 



stages resemble a good deal those of Marsilea, the thecae or 

 capsules containing sporules, or the bodies derived by ternar, 

 or quaternarisation. But they are similar, not dissimilar as 

 in Marsilea. 



Afterwards, of all the sporules, 8 or 10 to each sac, One 

 part only of one, continues its development. The three other 

 parts of that one, disappearing. All the others aborting, and 

 undergoing changes exactly such as they do in Isoetes. 



That one fourth becomes the reproductive germinating body, 

 and it remains enclosed in the parent cell, which again be- 

 comes covered by a testaceous outer opaque coat ; it presents 

 slight indications of its original sporous origin. 



Now, Pilularia is a more prolonged development than Isoe- 

 tes, for in this the sporules always evince their origin. 



Instead of Acrogens being said to be of indefinite germina- 

 tion, they should be said to produce a thallus or frond, before 

 they produce any part of the ordinary axis. All the higher 

 Acrogens agree in this, whereas Mr. V. shews that in Pilularia 

 the germinating point is prefixed. 



7. It is a remarkable fact, that dorsiferosity appears invari- 

 ably connected with the frondose form of the axis : this at once 

 suggests the non analogous (foliaceous) nature of the fronds of 

 Ferns. The dorsiferosity may be disguised, as in many He- 

 paticaB, but still, dissection shews that the origin in all, (see 

 Asolenium, Anthoceros etc.) is from the same layer, and that 

 when not obviously dorsiferous, it is due to Mechanical causes. 



