MACFARLANE: SYNCHRONISM IN PLANT STRUCTURES 323 



round Wilmington, N. C, it begins on April i8; in central New 

 Jersey, it opens on the 20th of May; in northern New York and 

 Minnesota it blooms from the 14th to the 26th of June. In eastern 

 central Maine the period is from the 8th to the 20th of July, while in 

 Labrador — the northern limit of the species — it finishes in mid-August. 

 Thus a period of fully five months is represented, and a longitudinal 

 area of about 2,000 miles is covered, in the floral maturation of this 

 one species. In connection with such records, and probably due to 

 the more gradual and even expenditure of environal heat stimuli is 

 the much more extended floral period of species in the cool north than 

 in the warm south. Thus while the double Crimson Rambler and 

 Dorothy Perkins roses show floral attractiveness from June 10 to 

 June 25 averagely round Philadelphia, on eastern Mt. Desert the 

 period extends from July 15 to August 30. 



Were the valuable records, inaugurated in 1892 for Canada by 

 Mackay, to be linked up with like records from widely distributed 

 stations in this country, and were all to be correlated with tempera- 

 ture or thermotactic and moisture or hydrotactic stimuli, as has in 

 part been done by the Canadian observers, a most valuable foundation 

 for the establishment of facts regarding the action of definite environal 

 stimuli would be made. 



A very wide field for exact study, still left practically untouched, 

 is the observation and recording of sporangial ripening and spore 

 dissemination in pteridophytic and bryophytic genera and species. 

 One or two references need only be made here. 



For years the writer was puzzled to know when spore-dissemination 

 took place in the sensitive fern {Onoclea sensibilis). Though the 

 green sporophylls shot up in late July and became greenish-brown in 

 autumn, opening of the modified pinnae and dissemination of spores 

 clearly did not take place before winter. Passing through a swampy 

 patch of this on March 24 of five years ago his clothes became browned 

 over with the shed product. Subsequent study has shown that this 

 event occurs averagely on March 25, and in any one patch or locality 

 with surprising synchronous exactness. Like observations should be 

 made for Onoclea Struthiopteris. 



The sudden and simultaneous elongation of the sporophores and 

 the subsequent rupture of the sporangia in such hepatics as Pellia 

 endiviaefolia is familiar to all in mid- April, but we still lack exact day 

 and hour records through succeeding years for the entire group of 

 scale mosses. 



The predicable manner in which, when fresh horse manure is 

 placed under bell jars in the now familiar laboratory experiment with 

 Pilobolus, an abundant crop of the black sporangia is shot forth on a 



