302 Lang.—Development of Cycadean Sporangia . 
of Stangeria is homologous with a sorus of microsporangia, 
in which only one sporangium is present, so that the sorus 
as a whole had kept pace with the developing sporogenous 
mass. When the origin of the microsporangium in the sorus 
is taken into account, it is evident that there is little, if any, 
difference between this conclusion and the statement that the 
ovule is homologous with a microsporangium. It is not 
difficult to recognize the equivalent of the projecting tip of 
the nucellus in the divisions which take place in the wall 
of the microsporangium above the sporogenous tissue. These 
divisions are better represented in the microsporangium of 
Zamia than in that of Stangeria ; in the former case, as 
Treub’s figures 1 show, they lead to the development of a 
pointed tip to the sporangium, which presents a striking 
resemblance to the apex of the nucellus of the ovule. There 
remains only the integument to be considered. The pro¬ 
jecting portion of this is clearly unrepresented in the micro¬ 
sporangium, and, on the view here suggested, would be 
regarded as an annular upgrowth, around the apex of the 
nucellus, of the bulky sporangial wall, or, which comes to 
the same thing, of the edge of the receptacle which had kept 
pace with the single sporangium. It will be evident from 
this comparison of the ovule with the microsporangium, and 
from the mode of origin of the integument suggested as prob¬ 
able, that the ovule is not regarded as a sporangium sunken 
in a lobe of the sporophyll. The facts appear to the author 
more naturally explained, when we compare the ovule to 
a sorus consisting of a single sporangium, which develops on 
the whole similarly to a microsporangium, save that it is 
bulkier, and the wall from the first thicker. 
If the more advanced ovule, say at the period of pollina¬ 
tion, be compared with the mature microsporangium, it is not 
surprising to find nearly all traces of the structure of the 
epidermal layer, adapted for dehiscence in the microspor¬ 
angium, absent in the ovule. It may, however, be pointed 
out that in the Cycadean type of ovule we have a mega- 
1 Treub, loc cit., 1885, PI. II, Fig. 4. 
