440 o^ APOsrouT i:^ poltstichum axgul^re. 



sinus (figs. 4 & 5). Since that date growtli has continued, tliougli 

 slowly, with the result that it is now an undoubted prothaUus, 

 though much thicker in substance than those produced by exten- 

 sion of the pinnule-tips. 



From these observations it will be seen that the formation of 

 the prothaUus in this case is preceded bj a very different series 

 of phenomena from those already recorded. In the one case the 

 prothalli are simple extensions of the cellular substance of the tips 

 of the pinnules, commencing at points quite beyond the venation, 

 and, so fixr as I have observed, produce no root-hairs unless 

 brought into contact with the soil. In the other case, however, 

 the prothaUus is a direct outgrowth of the tip of a veinlet pro- 

 truded through the upper surface of the pinnule, and at once 

 produces root-hairs in abundance long before it assumes any 

 other characteristic of a prothaUus ; and, finally, the resulting 

 prothaUus is much thicker in substance. Whether archegoma 

 or anthcridia are present upon the solitary specimen I have had 

 under examination, I cannot say, as the disturbance necessary 

 for microscopic scrutiny would probably have been more destruc- 

 tive than profitable. 



These excrescences, it will be observed, bear several striking 

 resemblances to the pear-shaped pseudobulbils first observed in 

 Athyrmm 'Filix-foemina^ var. clarissima. Their size, shape, and the 

 production at an early stage of radiating root-hairs are peculiarly 

 akin, as also the dilatation of the free end of the body into a 

 prothaUus; on the other hand, they are differentiated by their 

 isolation and independent position with regard to the sorus. 



I wiU conclude my remarks by pointing out that in all three cases 

 of apospory now observed there appears correlated with the pheno- 

 menon a marked elongation of the ultimate divisions of the frond. 

 Athyrium Filix-foemina^ var, clarissima^ is very remarkable for 

 this character; and on the two species of Folystichum the lower 

 pinnse are so characterized, while the upper pinnse, which nearly 

 approach the normal form, are comparatively barren of prothalli- 

 I mention this as it may form a clue to the discovery of t?ie phe- 

 nomenon in other Ferns which, like the one under special notice, 

 may only require close treatment to yield simUar results. I ^"^ 

 therefore sanguine that other workers, in not only British, but 

 exotic Ferns, may thus light upon new instances of the pheno- 

 menon in question, and so increase the opportunities of com- 

 pletely studying it. 



