THE ADULT Sl'UKOI'H\ I 1 



113 



mmthostachys. Th rough the kindness of Prof. L. I.. Burlingame I have also had 

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

 Helminthostach ys. 



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

 (). moluccanum (and this is true also ot 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 " bands. 



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



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 the individual sporangia are differentiated 

 later. The sporangia arise from this sporangiogenic 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 



Development of the sporangium in Ophioglossum pendulum. The darkly shaded nuclei in A mark tin- archesporium; 1. tapetuni; 

 sp, sporogenous tissue. A is a longitudinal section; B, a cross-section; C, part ol B, more highly magnified; l>. 

 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 of the sporangiogenic band. I he nil 

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



