404 Annals of the Carnegie Museum. 



to bear fruit. Usually the seedlings are in such a position as would 

 indicate that the acorn had been secreted by bird or animal, as for 

 instance, in the Arcfostaphylos mat of the heath, where young black 

 oaks are quite numerous at a distance of at least 40 rods from trees 

 old enough to bear acorns. It is well known that the blue jay and 

 the crow subsist largely upon wild fruits and mast during the winter 

 months and probably secrete quantities of larger nuts, acorns, etc., as 

 stores to resort to in cases of scarcity of food.^® The former bird is 

 an abundant permanent resident of Presque Isle, while the latter is 

 abundant during late fall and early spring, or even remaining on the 

 peninsula in limited numbers during the winter."" From this the dis- 

 semination of the oaks may be ascribed to these agents, in at least 

 a large measure. 



Vegetative dissemination by means of branching rhizomes, offshoots, 

 etc., is very prevalent in the earlier stages of the successions, especially 

 where the soil is loose and the formation is open. Among the more 

 conspicuous examples of this method of dissemination on Presque Isle 

 are : Panicum, A/idropogon, Ammophila, Myrica, Linuin, Aster, Soli- 

 dago, Arctostaphylos^ Jii7icus, Eleodiaris, Typha, Scirpus, Vagnera, 

 Unifolium, etc. In the more hydrophytic formations, as mentioned 

 for the inner zones around the lagoon, and also as represented by 

 Cephalanthns, Decodon, Castalia, Sphagnum, etc., this method is a 

 very prominent one. 



This brief sketch of the methods of dissemination on Presque Isle 

 shows that here, as elsewhere,®' water is the most important agent of 

 dissemination with beach plants ; wind yi'i'Ca. xerophytic (dry sand- 

 plain plants), or poophytic plants (grasses of the sand plain and wet 

 meadow, as Andropogon and Calaviagrostis') ; and anivials with hylo- 

 phytes (forest plants). 



A fact to be noted, in connection with the prevailing methods of 

 migration of plants to the new habitats on Presque Isle, is that the 

 species with northern relationships, such, for instance as Popuius, 

 Salix, Pi nits, Arctostaphylos, Triglochin palustris. Car ex oederi pic- 

 mila, Juncus balticus, etc., have, as a rule, a much greater ability to 



^^ Barrows, W. B., and Schwartz, E. A. "The Common Crow of the United 

 States." Div. Ornithology and Mammalogy, U. S. Dept. Agr. Bull. 6: 79-87, 

 1895 ; and Beal, F. E. L. " Some Common Birds in Their Relation to Agriculture." 

 U. S. Dept. Agr., Farmers' Bulletin No. 54 : 14-17, 1898. 



90 Todd. W. E. C. /. c, pp. 565-566. 



91 Clements, F. S. /. r., p. 218. 



