2 S3 BOTANICAL GAZETTE. 



the cavities, but partially also through the layers of tissue into the 

 surrounding water." 



In the light of these facts vve can perceive how the interior of a 

 water-plant may become of more importance to it than the exterior, 

 for most physiological purposes, and under the circumstances it is 

 not strange that we find such important organs of the metastatic pro- 

 cess as the hairs, transferred from the exterior to the interior, where 

 the amount of surface exposed to the interchanging gases is many 

 times greater than that exposed to the external atmosphere. 



Treol(?SS Prairies. — Mr. Tiiomas Meehan remarked that the 

 absence of timber or arborescent growth on the grassy i)rairies of 

 America still continued to be a matter of controversy, but he be- 

 lieved that in the light of accumulating evidence, we might now come 

 to a positive decision in regard to the question. The most prevalent 

 belief had been that trees would not grow on these prairies, — and we 

 have had theories relating to soil or climate, to show why they could 

 not grow. Then there were others who believed that trees did grow 

 there in ancient times, but had been burnt off and kept burnt off by 

 annual fires. 



Mr. Meehan considered in detail the authors who had propound- 

 ed various theories, and the distinguished men who had advocated 

 them, and said that it was evident climiUe could have nochmg to do 

 with the question, because in these prairie regions there were often 

 large belts of timber lands, projected like huge arms into the grassy 

 regions, with precisely the same climatal conditions over both. 

 That the soil was not unfavorable, was proved now by the artificial 

 plantations everywhere successful, and that the soil was unfavorable 

 to the germination of tree seed, as suggested by Prof. Whitney, was 

 on the face of it untenable from the fiict that it required but the same 

 conditions for the seeds of trees as for those of herbaceous plants, the 

 number of species of which on the prairies was well known to be 

 very large. Another great gain to our present knowledge was that 

 since the annual firing of the grassy prairies had been discontinued by 

 the advance of civilization, the timber was everywhere encroaching 

 on them. Among the f.tcts which he offered in proof of this, was a 

 reference to p. 505 of the 7th Report of the Geological Survey of 

 Indiana, where Dr. Schneck shows how land which was once grassy 

 prairie, is now covered with a luxuriant growth of forest trees ; to the 

 evidence of Major Hotchkiss, Geologist of Staunton, Virginia, that 

 the Shenandoah Valley, now heavily timbered, was clear of trees in 

 the early history of Virginia; to the discovery of buffalo bones, in 

 caves near Stroudsburg, Pa., by Dr. Jose]:)h Leidy, — now a timbered 

 region, the buffalo only existing in open, grassy countries ;*' and to va- 

 rious traditions of settlers in some valleys now timbered, that the 

 land was once clear of trees. He pointed out that in all known parts 

 of the United States at the present time, except the arid regions, 



*8iu,^e the readin.o; of tlie paper, it lias been bronsjlit to the attention of 

 the author, tliat lliu bones may have ()jloa;^2cl to tiie Wood Buffalo. 



