﻿I76 REPRODUCTIVE STRUCTURES 



bilus yet observed in the Cycadeoideis. This fruit, as shown in the transverse sec- 

 tion cut through its broadest portion, figure 93, is only 7 nun. in diameter, and hence 

 comparable in size to some of the smallest of the silicified cordaitean strobili from 

 the flint nodules of Grand Croix. Although so minute, the central cone is 

 distinct, as well as the series of thirteen fronds of the outer staminate disk, even 

 the bundle system of the rachides being in part, if not entirely, indicated by pre- 

 served xylem cells. Whether the microsporophylls of the disk are bipinnate, or 

 simply once-pinnate, with the synangia somewhat advanced in size and without 

 distinctly indicated structure, is not clear. It is, nevertheless, truly marvelous that 

 so minute a fructification should show so much, and at the same time it is a gage 

 of the rich reward that awaits the efforts of the patient student of the Cycadeoidetc 

 who would know all about this wonderfully conserved and fundamentally important 

 group of ancient plants. 



Additional facts concerning young fructification are given under the head of 

 bisporangiate axes. In the foregoing examples only a suggestion and merely 

 initial study of very young fruits has been attempted. The subject must be again 

 taken up. The object has been only to show the general character of axes which 

 are distinctly young — that is, have presumably never produced pollen or that 

 simply bear unfertilized ovules. However, these isolated examples show at once 

 the richness of the material at hand and the practical impossibility of reasonably 

 defining individual species and even genera in the absence of much wider study. 

 Before such studv has been made, specific and generic terms can be employed only 

 in an arbitrarv manner, though, nevertheless, they are a well-nigh indispensable con- 

 venience. Furthermore, in the absence of entire series of young fructifications cut in 

 median longitudinal section from trunks in different stages of growth, it is very 

 clear that we can have but an imperfect knowledge of the varied phenomena of fruit 

 growth, and of monoecious, dioecious, and bisexual conditions in the Cycadeoidese. 



THE YOUNG OVULATE AXES OF CYCADEOIDEA DACOTENSIS. 



(Study of Trunk No. 214. Cf. figure 94.) 



In all instances of young fructifications described above the strobili are for the 

 greater part young in the sense of presumably never having produced either mature 

 pollen or ovules ready for fertilization. But we now come to the consideration of 

 a wonderful series of strobili, including pollen-bearing flowers and ovulate cones, all 

 from the same trunk and furnishing far more definite testimony than almost any 

 number of isolated examples ever can. It was early seen that intensive study of 

 the trunks from the Black Hills must yield far better results than a partial study 

 of many forms. For this purpose trunk 214, photographed on plate vi, No. 8, 

 was early selected. This specimen is nearly perfect in preservation, little or not at 

 all crushed, sub-spherical in form, and about 45 cm. in diameter. An appression 

 face at its base shows that it grew in a clump and must have begun as a low grow- 

 ing branch of a larger and older central stem. As collected the trunk was broken 

 into two nearly equal closely fitting parts along a line roughly following its middle 



