SCIENCE-GOSSIP. 



175 



to be found in the higher regions (over 6,ooo 

 feet) in this part of the Sierra Nevada. The 

 scarcity of trees on the lower slopes and the 

 complete absence of larches or pines on the higher 

 parts, coupled with their general barrenness, due 

 in great measure to the scarcity of rain in the 

 summer months, give to the Sierra Nevada a very 

 desolate appearance as compared with the Alps or 

 the Pyrenees. In the last cultivated fields — if the 

 mere scratching of the surface of the soil and the 

 scattering of a handful or two of rye can be called 

 such — at an elevation of about 7,000 feet, several 

 plants of Gagea arvensis, R. Sch , were still in 

 flower, growing with Muscari racemosum, Dc. Near 

 these fields a quantity of Primula clatior, Jacq., was 

 growing by the side of a rivulet, but none of the 

 smaller species of primula, so conspicuous in the 

 Alps, were noticed in the higher regions. 



It was not until we reached an elevation of about 

 7,500 feet that we came upon the strictly Alpine 

 flora of the range. Among the first plants noticed 

 at this elevation was Fritillaria messanensis, Raf., a 

 species with glaucous leaves, and two dull purplish 

 flowers very slightly chequered. Its leaves were 

 often much infested by a species of Puccinia. Near 

 the Fritillaria was a crocus, probably C. nudiflorus, 

 Sm., the leaves of which were only then visible. 

 Soon after these plants began to appear we crossed 

 one of the lower cols and entered the Corral de 

 Veleta, a kind of cirque composed of the principal 

 peaks of the range, Alcazabar, Mulhahacen and 

 Veleta, which now burst magnificently into view. 

 Large patches of still unmelted snow covered a 

 considerable area of the Corral, and the best Alpine 

 plants were generally to be found in their vicinity, 

 as owing to the scarcity of rain the vegetation is, 

 to a great extent, dependent upon it. Prominent 

 among these plants was Ranunculus acctosellcefolius, 

 Bss., allied to R. glacialis of the Alps, but readily 

 distinguished by its long pointed leaves, wider 

 and fringed at the base, somewhat like those 

 of Rumcx acetosella, L. ; growing with it, but 

 very much rarer, was Ratiuncu'us demissus, Dc, 

 a yellow species with single- flowered peduncules 

 springing from a rosette of spreading root leaves. 

 Other good plants noticed were Viola nevadensis, 

 Bss., a species with small spathulate leaves grow- 

 ing in dense spreading tufts, Draba hispanica, Bss., 

 similar to our Draba aizoides, L., but with a hirsute 

 peduncule, and Plantago nivalis, Bss., a small species 

 with a thick root stock and spreading silvery leaves, 

 which generally grew very close to the melting snow. 



The most familiar plant growing in this elevated 

 region was Montia fontanel, L., which was very 

 abundant in the tiny rivulets which trickled down 

 the mountain side, and close to which Gentiana 

 verna, L., appeared from time to time. Last year's 

 dead flower stalks of a species of Eryngium (pro- 

 bably E. glaciale, Bss.) were noticed, but no living 



specimens, and a number of other plants still 

 presented a dry 'and withered appearance, not 

 having yet started into growth for the year, so 

 doubtless the region would yield a larger supply of 

 botanical treasures during July. 



On the top of the Culeta de Vacares, about 9,000 

 feet, the highest point to which we could induce 

 our guide to take us, Artemisia granatensis, Bss., was 

 not uncommon on the bare stony ground between 

 the patches of snow. It was not yet in flower, but 

 though small and obscure it attracted the attention 

 of our guide, who had remained quite impassive 

 before the handsomer plants below, as he hailed it 

 with delight and constantly directed my attention 

 to it. It is known by the natives under the name 

 of Manzanilla, and is much used in the preparation 

 of simples and for flavouring the sherry that goes 

 by that name. As a strong wind was blowing at 

 the top of the Culeta, from whence we looked down 

 upon the still frozen Laguna de Vacares, we rapidly 

 descended, soon leaving the snow behind, much to 

 the relief of the guide, whose flimsy aspargates, 

 or shoes with canvas tops and soles of matted 

 hemp, formed a very insufficient protection against 

 it. Our hospitable quarters were reached about 

 6 p.m., and a most enjoyable botanical excursion 

 was brought to a close. 

 Lewes; August 2nd, 1895. 



BIOLOGICAL DISTRIBUTION. 



T T must have frequently occurred to many 

 thinking people that the usual theory of 

 climatic influence can insufficiently account for 

 the geographical distribution of animals and 

 plants on large continents. Dr. C. Hart Merriam 

 has been conducting systematic research into the 

 subject in North America. He deals with the three 

 main zones of life found there. These are the 

 tropical, the austral and the boreal. Dr. Hart 

 Merriam treats only with the vegetation of these 

 regions, and the reason for the characteristic 

 species of each remaining therein, without extend- 

 ing over the adjoining regions. His theories are 

 that the northward distribution is determined by 

 the total quantity of heat, or the sum of effective 

 temperatures. The Transisian zone between the 

 boreal and austral regions is determined by the 

 mean temperature of the hottest part of the year. 

 The sum of the effective heat is the constant, 

 obtained by adding together the excess of the daily 

 temperature above 43 Fahr., which is the minimum 

 at which active plant life begins. The effective 

 temperature begins in spring, when the daily mean 

 rises above 43 and continues to accumulate until 

 the autumn daily temperature becomes lower than 

 43 . Humidity proves to be of secondary impor- 

 tance in defining the regions of plants, and probably 

 of animals also. 



