1882.] 



AND HORTICULTURIST. 



215 



stick— not even the Hawthorn in blossom on 

 this 24th day of May— and all because this im- 

 mense mass of ice has pressed more heavily than 

 usual against the north-eastern shores of our 

 continent. 



The time will come when we shall have 

 weather stations connected by telegraph in these 

 arctic regions; and blockhouses, well provis- 

 ioned, stretching out from one to another like a 

 chain of forts, and the great arctic problem will 

 be solved, and, there can be no doubt, to the 

 immense profit of all mankind. 



Transpiration of Plants. — Dr. J. M. Anders, 

 of the Philadelphia Academy of Natural Sciences, 

 who has already contributed some valuable pa- 

 pers on the transpiration of plants, gives some 

 more valuable facts in the January number of 

 the American Naturalist. He finds that one 

 square foot of naked soil will evaporate six times 

 as much moisture as a square foot of leaf surface ; 

 I but a forest has twelve times more leaf surface 

 than the earth surface on which the trees grow, 

 and, hence, the evaporation from a square foot of 

 forest-land is just double that of a naked surface. 

 He further finds that, say in the vicinity of 

 Philadelphia, twelve inches of annual rainfall is 

 given off during the leafy season of six months, 

 which is about half the annual rainfall. It 

 would thus seem that trees have very little to do 

 with the feeding of springs. It is sometimes 

 supposed that the trees retain snow, which melts 

 more slowly under the trees than in the sun- 

 shine, and that it, therefore, runs slowly into 

 the streams instead of melting rapidly in the 

 sun where the trees are absent ; but Dr. Anders 

 shows that the earth under trees is in a very ab- 

 sorptive condition, and that the slowly-melting 

 snow is taken up gradually by the earth under 

 the trees, in order to form the great reservoir of 

 moisture which is to supply the enormous sum- 

 mer demand from the leaves. Another interest- 

 ing conclusion, bearing on the literature of for- 

 ests and climate, may be drawn from these ob- 

 servations of Dr. Anders — namely, the trees 

 have to receive this moisture before they can 

 give it out again, and we may, therefore, say 

 trees are rather the result than the cause of a 

 moist climate. We have to look to the evapo- 

 rating power of the sun on immense tracts of 

 water and the condensing power of polar cur- 

 renta for our chief sources of rainfall, leaving to 

 trees the playing of a very small part in the 

 operation. — Independent. 



Selaginella Victoria. — Queen Victoria is 

 botanically honored by having one of the grand- 

 est flowers named for her, the famous Water 

 Lily of the Amazon River — Victoria regia. 

 Here we have her name associated with one of 

 the lowliest classes, a class which has no flowers 

 at all. It was on account of the apparent want 

 of flowers, that Linnaeus named this class of 

 plants Cryptogamia, w^hich may perhaps be ex- 

 plained as that class which perfects its seeds in 

 secret, although, critically, the spore of a fern 

 or Lycopodium by which reproduction is carried 

 on, is different in its nature from a seed. A fern 

 spore germinates, expands, and then the func- 

 tions of fertilization is effected, and the new 

 growth proceeds from the union ; but in the 

 ordinary seed fertilization precedes the forma- 

 tion. A seed is a sort of bud which follows pol- 

 linization ; a spore is a bud which precedes the 

 act. 



To the general observer there is in the ap- 

 pearance of some Lycopodiums and Selaginellas, 

 much in common with pines or other members of 

 the Coniferous class. But the laws of cell growth 

 at once divides them. Wood is made from the 

 gemmation of the cells. In the cells of coni- 

 ferse, the last formed of this year will grow next 

 in a lateral direction, and form a new layer of 

 wood around the last year's layer, and so con- 

 tinue from year to year, making an annual layer 

 of wood ; but these Cryptogaraic plants have no 

 such power of lateral growth. The cells at the 

 end of the growing point live over to next year, 

 as do the cells of the pine, but they only make 

 the new cell growth in the longitudinal direc- 

 tion, and not in the lateral one. Otherwise, cell 

 growth is very much the same in both cases. 

 The underground stem of the fern, Rhizome 

 the botanist calls it, goes on perhaps for an age, 

 making new cells out of the old ones, and leav- 

 ing the dead ones behind ; and just so do the 

 cells of a tree. The last year's cells die soon 

 after the new circle of wood is formed, and all 

 the circles of wood which form the trunk of a 

 tree, with the exception of the few circles near 

 the circumference, are as dead as are those be- 

 hind the tip of a fern rhizome. If there were a 

 lateral as well as a longitudinal growth ; if the 

 stem of a fern could go on thickening from year 

 to year, there might not be so much difference 

 between a Selaginella and a Pine; for with the 

 identity of powers in this respect, there might 

 come differences in the morphological laws 

 which result in the other distinct characters. 



