492 Mr. Valentine on the Structure and Development 



connexion with this sul)ject I shall take the opportunity of observing, that 

 fronj a partial examination of Lycopod'mm and Isoetes, I believe Dr. Lindley 

 is also correct as to the pulverulent matter of those genera being abortive spo- 

 rules. I at first intended to add to this paper some general observations on 

 tlie several groups which compose the Cryptogamia of Linnaeus, but I now 

 think it more desirable to defer this until they have been separately submitted 

 to examination ; for without an accurate knowledge of their structure and 

 germination, it is impossible to arrive at a satisfactory conclusion as to their 

 affinities. I cannot help observing, however, that Dr. Lindley has not in my 

 opinion exercised his usual judgment in removing Equisetacece from Acrogeris 

 to Gymnosperms. The affinity which they have to the latter is entirely in their 

 aspect ; there is no obvious structural or physiological analogy between them. 

 The supposition of Brongniart, that the reproductive body is a naked ovule, 

 and the four filaments that surround it four grains of pollen, without the power, 

 according to Lindley, of performing their function, is contradictory ; for what 

 evidence have we of any fertile ovule without the agency of the male organ ? 

 Besides, this supposed ovule is admitted in the same paragraph to be a sporule, 

 and afterwards proved to be such by its germination. 



This account of P'llularia shows that it is incorrect to say of Aa-oge?is that 

 " germination takes place at no fixed point, but upon any part of the surface 

 of the spores ;" for it is quite certain in this instance that germination in- 

 variably takes place at a fixed spot, whicii may be pointed out before germi- 

 nation has commenced. It is at that part of the sporule indicated by the 

 three radiating lines which appear to have been produced by the pressure of 

 the three other sporules that originally helped to constitute the quaternary 

 union ; and as the spores of all the other tribes appear, according to Mohl, to 

 be developed in similar unions, it is most probable that similar lines indi- 

 cating a valvular dehiscence also exist on them. This is certainly the case in 

 some Mosses, for instance, in CEdipodium, and in Isoetes, Lycopod'mm, and 

 Osmunda regalis; and in those instances where such a structure is not visible, 

 it is probably owing to a thickening of the membrane, or a deposition of 

 opake matter on its surface, as in Pilularia. In the mature sporules of Pilu- 

 laria they can only be discovered by dissection, and in the abortive ones they 

 cannot be discovered at all after the first stages of their growth ; whilst, again, 



