TRANSFORMATION OF SPOROPHYLLARY. I 'J 'J 



plants had each from one to four partially transformed sporo- 

 phylls. These presented a great variety of stages in the transi- 

 tion, though in no case had the transformed sporophylls reached 

 the size and expansion of the vegetative leaves as in the case 

 of Onoclea sensibilis. They were quite young, however, and 

 probably later in the season would have been larger and more 

 expanded. 



These plants were nearly all removed to the laboratory at 

 the time in order to photograph and study them. In general 

 the transformation of the sporophylls of Onoclea striitJiiop- 

 teris agrees with that of Onoclea sensibilis in that the distal 

 portion of the leaf and of the pinnae expand more than the 

 proximal portion, these latter parts bearing either normal sporan- 

 gia and sori, or showing them in various stages of degradation 

 and suppression. At that time no prothalloid growths could be 

 discerned with the eye, or with the aid of a pocket lens. Per- 

 haps they might appear later in the season, since the sporophylls 

 were much younger than those on Onoclea sensibilis on which 

 they occurred. 



The results of these experiments are entirely in harmony 

 with a law which many recognize to exist between the vegetative 

 and reproductive functions of plants, and indeed animals as 

 well. They serve, however, to demonstrate clearly this relation 

 which in many cases has been observed empirically rather than 

 demonstrated by definite tests. In these ferns, the fact that 

 there is a complete differentiation between the sterile and fertile 

 leaves, and that the sterile leaves develop quite far in advance 

 of the fertile ones, makes the case peculiarly adapted to present 

 a beautiful demonstration of the law. A certain development 

 of the vegetative phase is necessary in order to provide for the 

 necessary nutriment which the reproductive phase requires. If 

 the vegetative leaves are destroyed or removed before this func- 

 tion is so far completed as to enable the complete development 

 of the reproductive phase, the latter will necessarily decrease, 

 and there will be an effort on the part of the plant to provide 

 as quickly as possible for the furtherance of the vegetative 

 functions. This can most quickly be attained by the partial or 

 complete expansion of leaves which had begun to be differen- 



