1884.] NATURAL SCIENCES OP PHILADELPHIA. 117 



Relation of Heat to the Sexes of Flowers. — He referred to his 

 former communications to the Academy regarding his discovery 

 that the male flowers or male organs of flowers entered on active 

 growth at a much lower temperature than excited tlie female, and 

 exhibited catkins and female flowers of the European hazel-nut, 

 Gorylus Avellana,}ViSt matured April 15, and which, for the first 

 time in several years past, had perfected themselves coterapora- 

 neously. This was the first winter for some time that there had 

 been a uniform low temperature the whole season. In other years 

 a few warm da3's in winter would advance the male flowers so that 

 they would mature weeks before the female flowers opened, hence 

 the females were generally unfertilized, and there were few or no 

 nuts. Under this law it was evident amentaceous plants could 

 not abound to any great extent in countries or in localities favor- 

 able to bringing forward the male flowers before there was steady 

 warmth enough to advance the female. He thought this was 

 likely to be the reason whj^ so many coniferous trees under culture 

 in the vicinity of Philadelphia bore scarcely any fertile seed in 

 their cones — a fact which had often been remarked in connection 

 especially with the Norway spruce. The male flowers would 

 mature before the female had advanced far enough to be receptive 

 of the pollen. 



Specif c Differences in Picea nigra — It was regarded as some- 

 what diflftcult to distinguish between the red and black spruces, 

 Mr. Meehan exhibited authentic specimens of these and the white 

 spruce, and pointed out the persistent character of the cones in 

 Picea nigra, to which his attention had been called b}^ Mr. Robt. 

 Douglas, of Waukegan, Illinois. They were still attached to the 

 branches exhibited. 



The Flowers of Platanus. — Having an opportunit}^ to examine 

 a large tree of Platanus occidentalism no exception could be found 

 to the rule that the pedicel proceeded from the third node in the 

 season's growth. It appeared also that in the formation of the 

 pedicel, the growth of the branch was always almost arrested — 

 but not sufflcientl3^ so but that it seemed to recover and make a 

 second growth. In many cases the annual growth was completely 

 suppressed, and only a terminal bud was formed just above the 

 axis of the pedicel ; but in most cases, another or secondary 

 growth followed the first temporary check and a shoot of several 

 nodes would be formed bej^ond the point of departure of the 

 pedicel. The same rule prevailed in Platanus orientalis. 



Variation in Symjolocos foetidus. — Mr. Meehan had made it a 

 point for some years to take, as opportunit}' ottered, some genus 

 of only a single species within a large range of territory, and note 

 the variation therein. In this wa}' we could often see a vast 

 amount of variation, which could not be started by an}^ hybridi- 

 zation with other forms, but which must have been produced by 

 some law of evolution within itself. p]ven though one might 

 believe himself to be quite familiar with the skunk cabbage, 



