Morphology * of Cycadean Sporangia . 435 
mechanism of dehiscence present close resemblances to Angio- 
pteris. Stomata are found on the sporangium. 
6. In the pollen-grain two cells are cut off from the large 
vegetative cell before germination. 
7. In the later stages of development the ovule resembles 
other Cycads. 
Conclusion. 
Several observers 1 have discussed the extent to which the 
Cycadaceae agree in the development and structure of their 
sporangia with the Marattiaceae on the one hand, on the 
other with Angiosperms. It will therefore be unnecessary 
to do more than point out in what respects Stangeria shows 
resemblances to these two groups, deferring a more detailed 
treatment of the subject until a larger body of facts has been 
accumulated. In this paper the microsporangia alone will be 
considered. 
The arrangement of the sporangia in sori and the mode 
of development of the latter agrees closely with Angiopteris , 
and this has rendered the terms sporangia and sorus more 
suitable than those applied to the parts of the stamen of 
Angiosperms. On the other hand the origin of the sporo- 
genous cells from the hypodermal layer, a distinct epidermis 
being present, is quite different from what takes place in any 
Vascular Cryptogam hitherto investigated ; and, except for 
the small number of sporogenous cells, is similar to their 
origin in the pollen-sac of an Angiosperm. In the present 
state of our knowledge of the details of the apical meristems 
of Cycads, it is impossible to properly estimate the weight 
to be attached to this. If, as seems probable, the apical 
meristem is stratified 2 , no single initial cell being present, 
the general agreement which has been found to exist between 
this mode of arrangement of the formative tissues and the 
1 Braun, Warming, Treub., loc. cit. 
2 Strasburger, Coniferen und Gnetaceen, p. 335, Taf, XXV, Fig. 36. 
