142 PROCEEDINGS OF THE ACADEMY OP [1884. 



On Rapid Changes in the History of Species. — Mr. Thomas 

 Meehan exhibited flowers of the remarkable Halesia 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 gener- 

 ally accepted, that the maxim of Ray " Natura non facit 

 saltum " itself needed 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 ;^ 

 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 b}- 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 variations of 

 similar characters would appear at times in widely separated 

 localities." 



In addition to the illustrations given in that paper, a remark- 

 able one was aflbrded by the Richardia sethiopica^ 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 vicinit}^ 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. What- 

 ever it may have been, it operated in bringing about a change of 

 character, without the intervention of seed, directly on the plant, 

 and in Tn&ny 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 them- 

 selves — 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 development of a species 

 from a solitary individual presupposes. 



Aside from the great value of this illustration of how the 

 whole character of a species might be modified simultaneously 



1 See Proc. Amer. Assoc. Ad. Science, vol. xxiii, p. B. 9. 



