THE ADULT SPOROPHYTE 



113 



mmthostachys. Through the kindness of Prof. L. L. Buriingame I have also had 

 an opportunity to examine some of his preparations of Ophioglossum reticulatum and 

 Helminthostachys. 



An examination of both longitudinal and cross sections of the young spike in 

 0. moluccanum (and this is true also of 0. pendulum) shows that they agree entirely 

 with Bower's account of the development in the species studied by him. There 



Fig. 83. 



A. Transverse section of a very young sporangiophore of Ophioglossum moluccanum. X150. 



B. Section of an older sporangiophore. X75. The shaded areas mark the " sporangiogenic' 



C. Part of B, more highly magnified. The nucleated cells mark the sporangial region. 



bands . 



seems to be no question that, as Bower first pointed out, there is formed a continuous 

 band of tissue on each side of the sporangiophore, this band being the so-called 

 "sporangiogenic" band, from which ithe individual sporangia' are differentiated 

 later. The sporangia' 'arise from thisi^sporangiogenid band at more or less definite 

 intervals,| these fertile areas being separated'. by bands of sterile tissue. In the 

 sporangial areas periclinal walls are formed by which an inner mass of tissue, the 



Fig. 84. 



Development of the sporangium in Ophioglossum pendulum. The darkly shaded nuclei in A mark the archesporium ; /, tapetuni; 

 spt sporogenous tissue. A is a longitudinal section; B, a cross-section; C, part of B, more highly magnified : D , section of two 

 mature sporangia. X8. 



archesporium, is separated from the outer cells which are to form the wall of the 

 future sporangium. The inner cells constituting the archesporium later give rise 

 to the masses of spores. Between the young sporangia there lie partitions or septa 

 formed from the intervening sterile cells Jof the sporangiogenic band. The cell 

 groups which form the archesporia and the sterile septa are derived from sister cells 



