Al'KIL 5, 1895.] 



SCIENCE. 



373 



cline in June, and many of the groups show 

 well marked June depressions, as will be 

 seen ironi my eurves (in article cited). 

 The dominant families show maxima before 

 June or after, but not one of them shows a 

 June maximum. The depression some- 

 times occurs in very homogeneous groups, 

 as the Scrophulariace;e, there being no par- 

 ticular distinctions between the early and 

 late ones. The gap sometimes separates 

 species of the same genus. As a rule, the 

 vernal Howers belong to plants of low habit 

 which bloom in the woodlands, which are 

 now warm and sunny, or upon the open 

 groimds. About June the former become 

 overshadowed by the leaves which have ap- 

 peared on the trees, and the latter bj'the later 

 more luxuriant vegetation. Thus the species 

 of Viola and Lifho^permiim produce attractive 

 flowers until about this time, when they 

 either stop blooming altogether, or resort to 

 the production of cleistogamic flowers. 



One fact, which was not mentioned in my 

 paper, but is shown in my cm-s-es, is that 

 the gi'oups of anthophilous insects show 

 the same tendency to form early or late 

 maxima, wliich emphasizes the importance 

 of the correlations of the two sets of more 

 or less mutually dependent organisms. 

 The Syrphid;e. Empidse and Andrenidje 

 show early maxima, while all of the other 

 families show late ones. In the case of the 

 dominant genera of bees, Anthophora, Synha- 

 lonia and Ogmia reach their maxima early, 

 but the other genera predominate late. 

 Xunutda breaks into a large early group and 

 a small late one, just like Andrcna, upon 

 which it is parasitic. 



In the case of our trees, I suspect that 

 the flowers were always produced before 

 the appearance of the leaves, an arrange- 

 ment which would be most favorable to their 

 anemophilous pollination. Mr. Harshlier- 

 ger certainly seems very wide of the mark 

 in explaining the retention by trees of their 

 adaptation for wind aid in transferring their 



pollen. In the first place, their height ex- 

 poses them to the wind in such a way as 

 to make wind pollination quite favorable, 

 while the wind may also interfere \vith in- 

 sect visits. The fact that the most highly 

 specialized flower visiting insects are not 

 so abundant in spring will not do, for they 

 are not the insects which are most likely tO' 

 favor incipient stages of en tomophily. The" 

 less specialized bees (Andrenid;e) and the 

 flower flies (Syrphidie) are most abundant 

 in spring, and they would be the most fa- 

 vorable guests in the less specialized states 

 of insect-adaptation. Moreover, flower- 

 loving insects are very abundant in the 

 woodlands in the spring before the leaves 

 appear, and that is the verj' time that the 

 wind pollinated trees are in bloom. Bj" re- 

 sorting to entomophily, the trees would only 

 come in competition with the terrestrial 

 flora, which is more favorably situated for 

 insect visits and is very attractive to the 

 earlj- insect fauna. 



The author states that " Trees of abnor- 

 mal habit frequently show atavism, flower- 

 ing in the late autumn, if except ion a 11 j'^ 

 warm." Such cases as HamameUs are ex- 

 amples. I am inclined to Foerete's* view 

 that the autumnal blooming is a case of 

 precocious development of a spring flower. 

 According to him, Hamamelis has distinct 

 liibernacula and in cold autumns holds over 

 until next sjiring. 



If the generally accepted flower theorj' is 

 true, one would expect to find the highest 

 specialized flowei-s at that part of the sea- 

 son when the most highly specialized flower 

 visiting insects are most abundant. But it 

 is hard to understand how Mr. Hai-shber- 

 ger could attribute this modification to 

 the Lepidoptera. As far as adaptation for 

 flower-pollination is concerned, the bees are 

 beyond (juestion the most highly special- 

 ized. Mi'illei-f says: "Bees, as the most 



*Bot. Gazette, XVII., 3, 1892. 



t Fertilization of Flowers, 595, 1883. 



