THE INDIVIDUALITY OF THE SPORANGIUM in 



be supported on a basis of comparison among Angiosperms, though it is 

 a less frequent change : examples are to be found in the coalescent ovules 

 of certain Loranthaceae, or in the confluent pollen-sacs of certain Gut- 

 tifeae, etc. Among Pteridophytes, on the other hand, the genera are so 

 isolated as a rule that the comparative argument is difficult to apply : and 



FIG. 61. 



Danaea ell'ptica, Smith./ Drawings illustrating partial septations of the sporangium. 

 A, tangential section through three sori, showing the loculi in ground plan : the septa are 



, , 



often thin, so that pairs of loculi are in close juxtaposition ; the loculi marked 

 tial seta. X 20. />' C D show such loculi 



the cells 



, 



are large, and show one or more partial septa. X 20. />', C, D, , show such loculi with 

 partial septa in greater detail : in D and E it is difficult to decide whether 

 marked (?) will develop as tapetum or as spore-mother-cells. X 150. 



in each case of a synangium it may be a question whether the structure 

 results from septation or from fusion. But without entering into these dis- 

 cussions at present, it is plain that either way the individuality of the 

 sporangium is lost in such cases, just as it is in the Angiospermic anthers, 

 and this is particularly clear where, as often happens, partial septa are found. 

 In summing up the considerations contained in the above pages, it may 

 be asserted for sporangia at large, that the individuality of the sporangium 



