22 BOTANICAL GAZETTE [JULY 
imbedded sporangia in the podocarps. It would appear more 
probable that this transformation had taken place in several lines 
of descent than that it had taken place in the supposed Cordaztes- 
Pinus line, and had then reversed itself in the supposed Pinus- 
Araucaria line. The only very obvious difference between the 
microsporophyll of Araucaria and Cordaites is that the pollen sacs 
are erect and terminal in the latter and reversed in the former. 
This is precisely the difference in the ovulate cones. 
But little evidence can be gathered from the gametophytes, 
owing to our ignorance of those of the Cordaitales. In both 
araucarians and cordaiteans the male gametophyte (4, 5, 36) is 
larger than in other modern conifers. It is uncertain whether 
the gametophyte of the cordaiteans had a more extensive prothallial 
tissue, like that of the araucarians (5, 7), or a more extensive 
spermatogenous tissue, like that of certain modern cycads (36, 42). 
If I correctly apprehend the abietinean theory of the descent of 
araucarians, it involves the assumptions that the original male 
gametophyte possessed a more or less extensive prothallial tissue 
and at least one antheridium; that in the course of evolution it 
lost its prothallial tissue with the exception of two primary cells, 
but retained the spermatogenous tissue of the antheridium (this 
would perhaps represent the cordaitean stage); that it further 
lost all of its spermatogenous tissue during its evolution into the 
Abietineae, except that part giving rise to two male cells;. and, 
finally, that in the course of the evolution of an abietinean into an 
araucarian the place of pollen deposition became shifted (for reasons 
not stated) to a point much farther away from the female game- 
tophyte, thereby necessitating the production of a more extensive 
prothallial tissue (36) to supply the needs of the larger amount of 
cytoplasm required -to fill the more extensive pollen tube. Such 
a course of evolution is presumably possible, though I am inclined 
to think that the evidence favoring it is yet very inadequate. 
In the present state of our knowledge the large size of the game- 
tophytes is a point of resemblance between araucarians and cor- 
daiteans, while the pine type of male gametophyte can be easily 
derived in the same manner from either by the reduction of either 
or both the prothallial or spermatogenous tissue. 
