278 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



tion, thus making untenable the theory that the action of light in pro- 

 ducing specific formative substances is necessary for the construction 

 of flowers, the perfection of the gametophytes, and their functional 

 activity in setting up the changes antecedent to the integration of the 

 seed. Stated in another form the relation of the flower to illumina- 

 tion is seen to be purely adaptational and whatever action the rays 

 may exert upon it must be classed as stimulative in their actual effects. 

 This will be still more vividly apparent when the matter of develop- 

 ment of sporophores, sporophylls, sporangia and spores is consid- 

 ered ; since the most diverse reactions are exhibited by the ferns 

 and fungi when deprived of illumination. 



Effect of Etiolation upon Spores and Sporangia of Ferns. — Spo- 

 rangia were entirely lacking from etiolated leaves of Asplc7iiu7n 

 platytteuron (p. 75), and the sporophylls of Botrychiimi (p. 81) 

 were atrophied in a very early stage of its development. No spo- 

 rangia could be found in Filix fragilis (p. 106), and the sporo- 

 phylls of Onoclca sensibilis and Osmuiida cinnamoniea were not 

 developed in etiolated cultures. No differentiation of the sporogenous 

 tissues ensued in Polystichtun acrostichoidcs, Fteris longifolia^ or 

 Woodwardia 7'adicans. The appearance of the sporangia in all of 

 the species mentioned usually occurs at the summit of the morpho- 

 logical development of the sporophyls, and the notabl}'^ incomplete 

 stage of differentiation of the tissues reached by all of the species in 

 darkness renders the formation of sporangia or the completion of 

 spores impossible. 



Goebel suggested that a relation between illumination and the 

 formation of sporangia in ferns similar to that of the higher plants 

 to light some time since, but chiefly with reference to a possibility 

 of the conversion of sporophyllary to foliar leaves and vice versa. 

 (Flora, 80: 116. 1895.) In many of the species of ferns examined 

 by etiolated methods with results as enumerated above, ample reserve 

 food was to be found in the rhizomes and all ferns agree in the pro- 

 duction of chlorophyl in darkness. Here, as in the higher plants, 

 the lack of the necessary condition of a certain completeness of 

 morphological differentiation of the sporophyll preHminary to the 

 development of sporangia rendered the formation of spores impos- 

 sible. The differentiation of the tissues in question is, as in the 

 higher plants, dependent upon the stimulating action of light. 



Sporophylls of Equisctum attained a development fairly com- 



