92 



SCIENCE. 



[N. S. Vol. I. No. 4. 



than for the piirpose of producing a joint 

 publication. As a rule, however, the young- 

 discoverer works alone, and he will most 

 likely find, before he gets to the publishing 

 stage, that his first discoveries have been 

 made earlier by others. He must choose 

 his subject according to his own taste. 

 Usually he will be led most easily to some 

 fresh result, if he reads and digests with 

 keen interest the latest publications of 

 others upon some growing subject. He 

 may, perhaps, perceive that one of these 

 papers has not exhausted all the possibili- 

 ties ; or he may, by an alteration in the 

 point of view, find himself enabled to ob- 

 tain the same result by a much shorter and 

 more satisfactory process. He must not 

 fear that he is giving his mind to a subject 

 too trivial. ISTo matter how slight the ad- 

 dition which he makes to the sum of knowl- 

 edge, it is yet an addition, and unless it is 

 superseded by the doing of the same thing 

 by some one else in a better manner, it 

 is a permanent contribution to science. 

 Some are helped greatly, at times, by 

 working first on some numerical illustra- 

 tion of the problem in hand ; others, again, 

 by a preliminary geometrical representa- 

 tion ; and the first path to any discovery 

 is not usually the best. It is sometimes 

 supposed that the mass of original work 

 done in so many countries and published 

 in so many languages makes it likelj'^ that 

 any ordinary piece of work will be over- 

 looked in the great mass. Nevertheless, 

 liter a scripta manet ; and what may now 

 seem an unimportant addition to an unim- 

 portant branch may probably one day, when 

 that branch is no longer unimportant, and 

 when its special history comes to be itself a 

 topic of discussion, receive its due recogni- 

 tion. Meantime, every little helps. The 

 most trifling addition to the actual sum of 

 knowledge will be at least useful as a step 

 to aid the next investigator ; but whether 

 important or unimportant, whether appre- 



ciative recognition comes or not, whether 

 others are helped or no one takes notice, 

 there is a degree of personal pleasure in the 

 mere fact of origiuation which is the just 

 and certain reward of every piece of suc- 

 cessful investigation. 



Emoey McClintock. 

 New Yokk. 



THE ORIGIN OF OUR VERNAL FLORA. 

 Those who have collected flowering plants 

 for manjr years, without a doubt have been 

 impressed with the wonderful regularity 

 and precision displayed in the successive 

 flowering of diiferent species, even genera of 

 plants. The character of the vernal flora in 

 the northern United States * depends on the 

 seasonal development of plants belonging to 

 different natural orders. Each plant, even 

 orders of plants, have definite times of ap- 

 pearance, when their flowers open, fertiliza- 

 tion takes place, and seeds are distributed. 

 At times, a lull or break in the continuity of 

 this floral procession takes place just be- 

 fore the true summer plants appear. Such 

 a break seems to occur in the neighborhood 

 of Philadelphia between the twenty-fifth day 

 of May and the tenth or fifteenth day of 

 June, when the first true summer plants 

 appear. Curiously enough, this period cor- 

 responds with the time of the ice saints in 

 the United States, when there is a possibil- 

 ity of frost over a large portion of our con- 



* Tlie advent of spring may properly be considered 

 as taking place at the approach of an isotherm one de- 

 gree higher than 42.8° F., the general limit of proto- 

 plasmic activity. Tliere is no temperature in the ex- 

 treme South, in the vicinity of the Gulf, below 43.8° 

 on the average, and there is therefore no advent of 

 spring; no real beginning of vegetation and recloth- 

 ing of trees vrith leaves. On February 1st, the 

 isotherm in question is found crossing the United 

 States from the vicinity of Cape Hatteras on the east 

 to the north of El Paso, then northward to the Pacific 

 near San Francisco Bay. The phenomena of ^nnter 

 are to be found north of that line. See Harper's 

 Slonthhj Slagiizine, May, 1894, page 874, article by 

 Mark W. Harrington. 



