DERIVATION OF THE FLORA AND FAUNA 335 



"was successfully reached by a giant tortoise"; already Wai.F.ack entertained the 

 same idea — a strictly terrestrial animal crossing the ocean. 



Some biogeographers prefer one dispersal agent, some another, most have 

 confidence in all, but it goes without saying that different types of plants and 

 animals have availed themselves of different kinds of transport. 1 shall quote 

 (H LICK [iig. 414) first. 



It is possible to go far toward u first diagnosis of the degree of a land's insularity by 

 noting how exclusively it is peopled by types with a known capacity for colonizing across 

 vast expanses of ocean. Our summary up to this point reveals very nearly which these 

 forms may be. Quite a majority of them, both plants and animals, show characters that har- 

 monize with wind-storm transportation. A respectable majority of the larger-seeded palms 

 and some tough-lived earth-inhabiting invertebrates, suggest transportation by water or on 

 drift-wood. Such seeds and invertebrate eggs as can withstand the digestive tracts of a bird, 

 have a very substantial travelling radius by that means, easy 500 miles in the routine 

 seasonal migrations, and possibly stretching in the extremest cases to almost transoceanic 

 distances. . . . Dioecious plants and separate-sexed animals are statistically at a disadvan- 

 tage, as compared to the reversed condition, because of their jioorer chance of achieving 

 fertilization. The ability to take a journey in a gravid condition helps the chances greatly. 



"Types with a known capacity for colonizing" — GULlCK proceeds from 

 what should be proved, for their occurrence on isolated islands is in itself no 

 proof of oceanity. Under his angle the great number of dioecious endemic 

 phanerogams in Hawaii ought to have surprised him. It almost seems as if he 

 believed that entire specimens with roots and all managed to reach a distant 

 island and get established; surely, if only a male or an unfertilized female arrived) 

 all was in vain until a mate of the opposite sex turned up; a pregnant female 

 would of course do better (bye the bye, WALLACE tells a story of a pregnant 

 boa constrictor arriving on a West Indian island with drift-wood and in good 

 condition). I guess we can leave these chances aside, for plants spread by 

 means of seeds, and whether wind-blown, epizoic or endozoic (provided they 

 do not, as many assert, discharge their droppings soon after the departure), 

 there is every chance that more than one seed of the same kind is brought; a 

 single many-seeded berry is enough, and a bird picking drupes fills his stomach. 

 A seed portion of a dioecious species gives, under ordinary conditions, 50 % of 

 each sex. In the Hawaiian flora we find, GULICK says (p. 418), "a preponderance 

 of plants spread by wind-carried spores and minute seeds" ; species with drupes 

 and berries are, however, numerous. As an exainple of a presumably definite 

 case of bird rather than wind carriage he mentions the Hawaiian species of 

 Vaccinium, which he derives from North America. Their presence is most in- 

 teresting, "as the distances involved must be very close to the extreme physio- 

 logical maximum that land birds can traverse, and still carry fruit seeds in their 

 droppings". To me it appears as a bad case of constipation. Besides, the Ha- 

 waiian Vaccinia are not related to North^ American groups but belong to a 

 special section. 



Mavr, an extreme "oceanist ' who refuses to admit land connections for 

 either Fiji or New Caledonia, in his paper on the Pacific bird fauna [179) includes 



