250 On Azolla and Salvinia. 



opinion which appears to be correct to some degree at 

 least. 



The anomaly observable in the numerous spherical pedi- 

 celled secondary capsules, through which the previously free 

 spores become enclosed in cells, which subsequently partly 

 or entirely coalescing form solid masses, in which the spores 

 are then imbedded, is, I think, very remarkable. 



The appearance, however, of these cells, which exist in 

 both genera, and which seem to be developed from the 

 inner surface of the secondary capsules, either corresponding 

 to and enclosing several spores, or at least as in Salvinia 

 occasionally arising opposite single ones, is not organic : 

 it is that of the mammilla of the yellow sac. The young 

 masses indeed are like it elastic, and it is evident that 

 there is neither a common nor a partial membrane. 



It is difficult to believe that these masses are abortive 

 developments, particularly when the appearance of grume or 

 molecules in the imbedded spores, and the obvious 

 hypothetical capability of growth of the masses is consider- 

 ed. Direct observation on this head is required, and if it be 

 found that they do produce young plants, and that the growths 

 take place from more than one of the imbedded spores, 

 an analogy may become presented to pluri-embryonate 

 Gymnospermous plants. 



I know of no parallel instances to the lobes surmount- 

 ing the yellow sac in Azolla, and especially to the tissue, 

 which on being pulled separates in the form of radicels. There 

 are reasons, as I have stated, for supposing the lobes them- 

 selves to be modifications of the spores, and comparing 

 the early number of nuclei or points of condensation with the 

 mature number of the lobes, the opinion becomes suggested, 

 that these receive their developments at the expense of others. 

 However this may be, their analogy with the solid masses of 

 the spherical pedicellate secondary capsules appears suffi- 

 ciently obvious. They are not in any way to be referred to 



