2 8o 



NA TURE 



[May 6, 1909 



drift-zone was the low growth of the famihar Vcs- 

 caprae formation — long, trailing, rooting shoots of 

 Ipoinoea Pcs-caprae, with runners of Spinifex form- 

 ing a network with which was associated some low- 

 growing leguminous species, and here and there tall 

 grasses, sedges, and other familiar strand-plants. 

 Beyond this a }'Oung strand-forest of trees and 

 shrubs recalled the similar formation on the Javan 

 coast. Most conspicuous were tall Casuarinas (C 

 equisetifolia), 40 feet to 50 feet high, while slender 

 climbing plants, such as Cassytha, Canavalia, Vitis 

 tnfolia, and others formed an almost continuous 

 mass of foliage. Among the trees, Calophyllum 

 Inophylluni, Terminalia Catappa, and the beautiful 



and much of the flora remains, therefore, still unex- 

 plored. Nevertheless, the results bring the total 

 number of species collected up to 137; the ferns have 

 not materially increased in number, but the seed- 

 plants have risen to ninety-two species. Of the 

 strand-flora, two-thirds are species which are cosmo- 

 politan on tropical coasts, and the plants of the in- 

 terior are also cosmopolitan, or represent the com- 

 monest species which are widely spread over the old- 

 world tropics. Nitrogen-fixing bacteria were found in 

 abundance in the soil. As regards the means by 

 which the islands have been colonised, it is esti- 

 mated that of the seed-plants 39 per cent, to 72 per 

 cent, have been brought b)' sea-currents, 10 per cent, 

 to ig per cent, by birds, and 16 

 per cent, to 30 per cent, by air- 

 currents; air-currents are also re- 

 sponsible for the presence of the 

 ferns and lower cryptogams. 



In " Camp-fires on Desert and 

 Lava " the author gives a 

 graphic account of the vegetation 

 and animal life of the desert 

 country in the extreme south-west 

 of Arizona and the Mexican bor- 

 derland. The book is a diary of 

 a trip led by Dr. D. T. Mac- 

 Dougal, director of the recently 

 formed Desert Botanical Labora- 

 tory at Tucson, Arizona. The 

 ostensible object of the trip was 

 the exploration of the unknown 

 country round about Pinacate 

 Peak, which lies between the in- 

 ternational boundary and the 

 Gulf of California. Mr. Godfrey 

 Sykes, geographer to the expedi- 

 tion, supplies two new maps 

 which show the route of the ex- 

 pedition and add considerably to 

 geographical knowledge of the 

 Pinacate district. But it is the 

 naturalist and, above all, the 

 botanist, who will find most of 

 interest in the book. 



Mr. Hornaday poses as Dr. 

 f^i/^uj, <S^^*i^ / ir''»!^^J^ - . ^^ ^S^^^ MacDougal's pupil, but he has a 



' ■ -*^ - :^ - i.K . wL .SiiL,*.-, .. *«»iA^^, .,'■' £« ii ■■ ^kS iceen eye for the plants, and has 



given as graphic an account as we 

 have seen of the remarkable 

 adaptations of plant-life to the 

 almost waterless conditions of 

 the sand-deserts or lava-strewn 

 |3lains and mountains. The nu- 

 merous excellent photographic 

 illustrations are a great help 

 towards realising the general 

 ecological conditions of the dis- 



FlG. 2. — The'Finest Organ-pipe Lucius. h rom Lamp Fucmjii Dc^cU ..nd l-av.,. trlct, aS Well aS thC habit of the 



Phoiograph by the author. Components of its flora. The 



various Cacti, such as the giant 

 white-flowered Barriiigtoiiia spcciosa, which has given cactus, or Saguaro (Cereus giganteus), the 

 a name to this type of strand-forest vegetation, were organ-pipe cactus {Cereus Thiirberi) (Fig. 2), 

 conspicuous. Coco-nut palms, clumps of screw-pine ' the Choya (Opuntia sp.), and the barrel cactus 

 (Pandanus), and large-leaved figs were also seen. (Echinocactus), the Ocatilla {Fotiqtiiera splcn- 

 Beyond the strand-forest a monotonous steppe-like i dens) — " next to the giant cactus the most monu- 

 vegetation of tall grasses and reeds, sometimes asso- , mental and picturesque thing of plant growth 

 ciated with climbing plants to form dense jungle, ex- j found in two hundred miles of fertile deserts," when 

 tended into the ravines and on to the steep sides ' in full leaf resembling a bouquet of green wands 

 far up on the cone. A deep ravine, rich in trees and ' held at the bottom by an invisible hand — the mesquite 

 shrubs, e.xtending half-way up the slopes of Rakata, tree (Prosopis veluliiia) — the most persistent bush-tree 

 promised a rich botanical harvest, but, unfortunately, , of the deserts, the leaves and beans of which are 

 the party was unable to make a way through the eaten by horses and cattle when grass is not obtain- 

 thicket with the equipment and time at its disposal, able, while its wood is the general stand-by for fuel 



NO. 2062, VOL. 80] 



