CH. IX] OBJECTIONS TO THE HYPOTHESIS 97 



Of the "swamped" genera, only about half are herbs, while 

 of the unswamped, herbs are 83 per cent. Of the unswamped 

 genera with no endemics, 85 per cent, are herbs, while of those 

 with endemics 80 per cent, are herbs. From these figures it 

 would seem that the evidence is just as good for the connection 

 of swamping and woody nature as of swamping and age. 



The Coniferae are probably older than the flowering plants, 

 and as they have no wides at all in New Zealand, this speaks in 

 favour of age, but they are also all woody plants. The Ferns, on 

 the other hand, which are probably older again, show very little 

 "swamping," only 5 generaoutof 31 exhibiting this phenomenon. 

 Of these it may be noted that three are the only tree-ferns in 

 New Zealand. The remaining two, and all the unswamped genera, 

 are herbaceous. It is evident that the question of swamping 

 must be disentangled from the question of the relatively greater 

 age of woody vegetation, but inasmuch as woody vegetation in 

 general is probably older than herbaceous, it seems probable 

 that swamping goes to some extent with age. 



Actual measurements show that the average range in New 

 Zealand of one species of a swamped genus is 509 miles, which 

 within a very close approximation is the same range as that of 

 the whole flora of New Zealand, and considerably more than the 

 average range of the total of the species endemic to New Zealand, 

 or New Zealand and its outlying islands, which is only 446. On 

 the whole, therefore, one may probably saj' that these "swamped" 

 genera are older than the unswamped. 



Further confirmation of this ^'iew may be obtained from the 

 fact that 45 of the swamped genera reach the outlying islands 

 round New Zealand, while only 27 of the unswamped do so, 

 though the latter are much more mmierous. 



There is a possibility that Avith mere passage of time species 

 may undergo change, and it may be that "swamping" is some- 

 thing of this nature. 



An important fact must be noticed in considering this objec- 

 tion, that the genera without "wides" behave just like those 

 that include such. They have (cf. the map of Gunnero in New 

 Zealand, p. 158) similar local distribution ; their centres of greatest 

 density are the same; their proportion of species belonging to 

 the different classes {i.e. the classes in order of area) is the same 

 when several genera are taken. If the endemic species of the 

 genera that possess wides are dying out before the competition 



