262 



SCIENCE. 



[N. S. Vol. XVII. No. 424 



in mode in curves is shown in the pine- 

 apple and chrysanthemum. 



Transgressive variation due to change 

 of anthotaxy is found in Iris. 



Contrasts and Resemblances between the 

 Sand Dune Floras of Cape Cod and 

 Lake Michigan: Henry C. Cowles, 

 Chicago, 111. 



Physically the dunes of these two regions 

 agree: (1) In the character of the sand, 

 except that larger grains are found at 

 Cape Cod; (2) in the general features of 

 dune formation and movement; and (3) 

 in the pronouncedly xerophytic conditions 

 for plant life. The following contrasts 

 were observed: (1) Obscure zonation on 

 the ocean beach (this is much less marked 

 on the bay side of Cape Cod) ; (2) a verti- 

 cal sea front on the dunes nearest the sea, 

 doubtless chiefly due to sea encroachment 

 (this feature is wanting at Nantucket) ; 



(3) the Cape Cod dunes are much lower, 



(4) less extensive, and (5) present a much 

 less- typical contour; (6) the dune move- 

 ment is much more rapid on the Cape, as 

 shown by self-registered measurements on 

 half -buried trees. 



Ecologically there is general similarity: 

 (1) In the vegetation forms of the two 

 regions; (2) in the wonderful endurance 

 of swamp plants which are encroached 

 upon; (3) in the general content and 

 dynamics of the associations (but on the 

 Cape lichen pioneer stages are often found 

 and pines do not always precede oaks). 

 The contrasts are: (1) The beach flora 

 does not show clear zonation on the ocean 

 side of the Cape, and the plants are hud- 

 dled at the foot of the fore-dunes ; (2) the 

 ocean beach (but not that of the bay shore) 

 has a much sparser plant covering than 

 does the lake beach; (3) half-buried plants 

 show a surprisingly vigorous leaf develop- 

 ment on the Cape dunes ; (4) the plant cov- 



ering on moving dunes is more dense at 

 Cape Cod; (5) tree shapes are less modi- 

 fied on the lake dunes; (6) some species 

 mesophytic in one region are xerophytic in 

 the other. 



Floristically the two regions are astonish- 

 ingly alike, the per cent, of common species 

 being as gi'eat or greater than would be 

 true for inland associations at such a dis- 

 tance. 



In conclusion, the resemblances are more 

 striking and more far-reaching than the 

 contrasts, showing that halophytic and 

 tidal factors are relatively unimportant in 

 determining sand-dune or even sand-beach 

 floras on Cape Cod. The contrasts which 

 exist are probably due, in the main, to dif- 

 ferences in moisture and wind relations. 

 In most respects the Cape conditions seem 

 to be the more severe, and yet the vegeta- 

 tion covering these is more dense and the 

 growth more vigorous. 



The Production of Neiu Varieties of 

 Oranges: Hekbeet J. Webber and 

 Walter T. Swingle. 

 The great desideratum of the orange in- 

 dustry at the present time is a hardy 

 variety that will be able to withstand the 

 occasional severe freezes without serious 

 injury. The deciduous trifoliate orange is 

 perfectly hardy as far north as Philadel- 

 phia, but its fruit is small and practically 

 worthless, though sometimes used for pre- 

 serves. Several years ago the writers 

 started experiments for the U. S. Depart- 

 ment of Agriculture, in the production 

 of a hardy orange by hybridizing the very 

 hardy trifoliate orange with varieties of 

 the ordinary sweet orange. Our aim has 

 been to secure a new hybrid orange that 

 would have the hardiness of the trifoliate 

 orange and the sweet, edible fruit of the 

 common orange. The experiments have 

 not yet been completed, but two hybrids 

 have been secured which possess decided 



