BOTAXY. 34:7 



some hint towards its solution ? If \ve take a flower-stalk of the common 

 plantain (plantago major) between the thumb and fingers, we can, by twist- 

 ing the stalk in one direction or the other, arrange its buds in any number of 

 rows that the law of phyllotaxis permits, two, three, five, eight, &c. As we 

 can thus pass from a higher to a lower number, or from a lower to a higher, at 

 pleasure, by simply twisting the stalk, that is, by introducing a constant dis- 

 turbance at every point of the stalk, it is plain that the mathematicians will 

 allow the organic law to be founded either upon a very high number of rows, 

 which by a constant interference is reduced to smaller numbers, or upon a 

 low number, which is modified into higher ones. The former had been the 

 view of Prof. Pierce, in his paper presented to the Cambridge meeting, viz. 

 that the organic law of vegetable growth contained, as a fundamental con- 

 stant, the surd towards which the series -J-, -, f, f, &c., approximates; and 

 that interferences with it, constant or nearly so in each botanical species, 

 produced the approximations. Dr. Hilgard, on the contrary, had sought for 

 the germ of the law of phyUotaxis in the numerical genesis of cells. Starting 

 with a primal cell generating a second, and assuming that the second requires 

 a time to come to maturity, during which the primal cell recuperates its 

 powers and produces a third, we have a law which gives the phyllotaxian 

 numbers. One cell generates a second, and then a third. The first and 

 second then simultaneously generate each one, which make the whole num- 

 ber five. The first, second, and third, are then mature enough to generate 

 each one, which makes the whole number eight. Five are then sufficiently 

 mature to generate each one cell, which raises the whole number to thir- 

 teen. Here, then, is a simple mode of conceiving of the genesis of cells, which 

 gives us at once the numbers that occur in phyllotaxis, and no others. But, 

 we need also the geometrical element, the position as well as the number 

 of the leaves ; and if we can obtain it from this same conception of numerical 

 genesis it will be a strong confirmation of the theory, that this lies at the 

 foundation of this organic law. Now, if we take a rosette of the house-leek, 

 for example, and number the leaves of the whorl in phyllotaxian order, we 

 shah 1 find the successive numbers actually placed in juxtaposition to those 

 which in our law of cell genesis would be their parents ; that is, 4 and 5 will 

 be placed at the base of 1 and 2; 6, 7, and 8 at the base of 1, 2, and 3, &c. 

 This conception of numerical genesis fulfils, therefore, the geometrical con- 

 ditions required, and thus asserts its claim to a fundamental position in any 

 theory of the organic law of vegetable growth. 



PEOTECTIXG INFLUENCE OF SNOW ON VEGETATION IN ARCTIC 



LATITUDES. 



Few of us at home can realize the protecting value of this warm coverlet 

 of snow. No eider-down in the cradle of an infant is tucked in more kindly 

 than the sleeping dress of winter about this feeble flower life. The first 

 warm snows of August and September falling on a thickly bleached carpet 

 of grasses, heaths, and willows, enshrine the flowery growths which nestle 

 round them in a non-conducting air-chamber; and as each successive snow 

 increases the thickness of the cover, we have, before the intense cold of win- 



