ON RAPID CHANGES IN THE HISTORY OF SPECIES. 521 



ON RAPID CHANGES IN THE HISTORY OF SPECIES. 



Mr. Thomas Meehan exhibited flowers of the remarkable Halc&ia noted at 

 page 32, and remarked on the wide divergence reached without any intervening 

 modifications from the original, and observed that it was another illustration of 

 what he thought must now be generally accepted, that the maxim of Ray " Natura 

 nonfacit sal/um" \tseM nttded. modification. He had called attention to this 

 particular departure, among others, in a paper before the American Association for 

 the Advancement of Science^ in 1874 ;i what he desired to do now was to emphasize 

 a few of the points brought out prominently in that paper, that " Variations in 

 species as in morphological changes in individuals, are by no means by gradual 

 modifications ; that suddenly formed and marked variations perpetuate themselves 

 from seeds, and behave in all respects as acknowledged species; and that varia- 

 tions of similar characters would appear at times in widely separated localities." 



In addition to the illustrations given in that paper, a remarkable one was 

 aff'orded by the Richardia cEthiopica^ the common "calla" of gardens, the present 

 season. Some four inches below the perfect flower a mere spathe was developed, 

 partially green, but mostly white, as usual, but in this case we do not call it a 

 spathe, but a huge bract. In other words, the usually naked flower-scape of the 

 Richardia had borne a bract. Flowers with a pair of more or less imperfect 

 spathes were not uncommon in some seasons ; the peculiarity of the present 

 season was the interval of several inches on the stem, which justified the term of 

 bract to the lower spathe. From the vicinity of Philadelphia numbers had been 

 brought to him, and others had been sent from Ohio, Indiana and Illinois — some 

 hundreds of miles apart. What was the peculiarity in this season over others 

 which induced the production of this bract, was one question. Whatever it may 

 have been, it operated in bringing about a change of character, without the 

 intervention of seed, directly on the plant, and in many widely separated places 

 at the same time. What is to prevent a law which operates exceptionally in one 

 season, operating again and in a regular and continuous way ? So far as we can 

 understand there can be no reason ; and, if it should, we have a new species, not 

 springing from a seed, or one individual plant — constituting one geographical 

 centre of creation from which all subsequent descendants emigrated and spread 

 themselves — but a whole brood of new individuals already widely distributed over 

 the earth's surface, and entirely freed from the "struggle for existence" which 

 the developement of a species from a solitary individual pre-supposes. 



Aside from the great value of this illustration of how the whole character of 

 a species might be modified simultaneously over a wide extent of country, it 

 afforded a lesson in environment. External circumstances may influence modi- 

 fication, but only in a line already prepared for modification. This must neces- 

 sarily be so, or change would be but blind accident, whereas palaeontology teaches 



1 See Froc. Amer. Assoc. Ad. Science, volume sxiii, p. B. 9. 



