1896.] Vegetative Phase of the Sporophyte. 353 



the Angiosperms the vegetative function can be assumed not 

 only by the floral envelopes, but also by the sporophyllary 

 organs, more commonly by the macrosporophylls, or gynse- 

 cium. In some cases these open and expand into green leaves 

 with the ovules, in a more or less imperfect stage of develop- 

 ment, exposed. Perhaps no definite experiments have been 

 carried out to demonstrate the cause of this transformation of 

 form and function. It is supposed to be due to either exces- 

 sive nutrition, or to some injury to the vegetative system of 

 the plant. While such cases are unsatisfactory because of the 

 lack of definite tests, they indicate that the sporophylls can 

 assume the form and function of foliar organs when there is 

 a disturbance of nutrition of a kind considered above. Since 

 these sporophylls are, from a morphological standpoint, con- 

 sidered homologous with the green leaves, this change of func- 

 tion is not incompatible with that theory. 



In the Pteridophytes direct experimentation proves beyond 

 a doubt, that the sporophylls can be made to assume the form 

 and function of the foliar organs by cutting off the latter, thus 

 disturbing the nutrition and forcing the vegetation function on 

 the sporophylls. The experiments performed upon Onoclea 

 sensibilis and 0. strut hiopteris may be cited. In these cases 

 after cutting off the early developed vegetative leaves the 

 sporophylls appeared later in all stages of transformation, some 

 complete vegetative leaves with only vestigial remnants in the 

 form of rudimentary indusia to indicate to which series of 

 organs they primarily belonged in the ontogeny of the plant. 

 Between these and perfect sporophylls all gradations of inter- 

 mediate forms occurred, the terminal portions of the sporophyll 

 and of the pinnse always being more fully expanded, while 

 the basal portions of the same partook more or less completely 

 of the true sporophyll. The details of the experiment and of 

 the gradations of the development are given elsewhere, and 

 cannot be dwelt upon here.. 



As an outgrowth of these experiments and observations a 

 second proposition mey be formulated as follows. Disturbed 

 nutrition, resulting from the loss of the carbon assimilating 

 organs of the sporophyte (vegetative leaves), may, and does, 



