492 Mr. Valentine o» flic Sfrminre and Development 



connexion with this subject I shall take tlie opportunity of observing, tliat 

 from a partial examination of Li/cojxxliinn and Isoëtes, 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 

 the several groups which compose the Cri/ptoganihi of Linnœus, but I now 

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

 to examination; for witliout an accurate knowledge of their structure and 

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

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

 opinion exercised his usual judgment in i-emoving Equlsetaceœ ïvom Acrugens 

 to Gi/mnosperni.s. 'ilie affinity which tliey 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 perforj;ing 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 PihiUtria shows that it is incorrect to say oi Aerogens that 

 " germination takes place at no fixed point, l)ut 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, which may be pointed out before germi- 

 nation has comn)enced. It is at tliat pait 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 Mold, 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 Œdipodiiim, und in Isoetes, Lycopodiitm, and 

 Osnnuida 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 PUularia. In the mature sporules of Pilu- 

 loria 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. 



