...condition of any polysporangiate sporophytc as we see it is the resultant of modifications such as these, operative during its descent. The problem will,...survival, and hence, other things being equal, increasing numbers of spores and of sporangia may be anticipated ; but in the heterosporous types reduction in...

...condition of any polysporangiate sporophyte as we see it is the resultant of modifications such as these operative during its descent. The problem will...place in the history to any or each of these factors. But in each case the physiological probability of any modification which the structure would suggest...

...other factors having been operative of which we are yet unaware ) the ant of modifications such as these, operative during its descent. The problem will,...survival, and hence, other things being equal, increasing numbers of spores and of sporangia may be anticipated ; but in the heterosporous types reduction in...

...condition of any polysporangiate sporophyte as we see it is the resultant of modifications such as these, operative during its descent. The problem will,...survival, and hence, other things being equal, increasing numbers of spores and of sporangia may be anticipated ; but in the heterosporous types reduction in...

...polysporangiate sporophyte us we see it is the resultant of modifications such as these, operative during ita descent. The problem will, therefore, be in each case...survival, and hence, other things being equal, increasing numbers of spores and of sporangia may be anticipated ; but in the heterosporous types reduction in...