628 



SCIENCE. 



[N. S. Vol. XXI. No. 538. 



published, those from Paris being the best; 

 2,100 i^lates are still unpublished. Each ob- 

 servatory publishes its own work and the com- 

 bination of the results has been left so far to 

 voluntary workers. One computer deduces 

 from about 300 plates, taken at nine places, a 

 parallax of 8."7996 ± .0021. 



Mr. J. E. Burbank then spoke on the 

 ' Records of Earthquake Disturbances on 

 Magnetographs of the Coast and Geodetic 

 Survey.' Such records occasionally show dis- 

 turbances markedly different from any usual 

 magnetic disturbance; thus in the last few 

 years some forty of them have been noted at 

 Baldwin, Kansas. The speaker had attempted 

 to compare all such disturbances found on 

 records from half a dozen observatories with 

 one another and with simultaneous records of 

 seismographs. In spite of marked differences 

 in time and duration there is so large a num- 

 ber of coincidences in time as to justify the 

 belief that they have a common cause in an 

 earthquake wave, although the speaker is not 

 prepared to present any theory of the phe- 

 nomena. Charles K. We ad, 



Secretary. 



THE TORREY BOTANICAL CLUB. 



Minutes of a meeting held March 14, 1905, 

 at the American Museum of Natural History. 



The first paper on the scientific program 

 was by Dr. N. L. Britton, and was entitled 

 ' A Botanical Cruise in the Bahamas.' 



The speaker had just returned from several 

 weeks' exploration in the Bahamas and gave a 

 general account of the trip. The numerous 

 islands — there are over 2,700 islands, keys and 

 projecting rocks — are all of the same general 

 type in that they consist of coral limestone. 

 The group is so scattered that there is con- 

 siderable variation in temperature and rain- 

 fall. 



A remarkable feature of the islands is the 

 abundant and almost impenetrable thickets 

 growing directly out of the rock ; in fact there 

 is very little soil except that known as ' red 

 land,' which occurs in the bottom of sink- 

 holes and locally in swales, and the ' white 

 land ' formed from the crumbled rock either 

 disintegrated in place or accumulated as sand 



dunes. These two formations represent prac- 

 tically all the tillable land of the islands. 



Owing to the ijorous nature of the material 

 there are no known permanent fresh-water 

 streams, although there are a number of salt- 

 water creeks of considerable size. Occasion- 

 ally there are fresh-water ponds and marshes, 

 mostly of small size. These very local ponds 

 and marshes furnish many of the botanical 

 novelties. Salt-water ponds which rise and 

 fall with the tide are abundant and sometimes 

 of large size. 



The Bahamas are very recent geologically, 

 the Bahaman uplift being placed not earlier 

 than the late Tertiary, so that they offer excel- 

 lent opportunities for the study of plant mi- 

 gration and evolution. 



The flora is of southern derivation, a large 

 number of the known indigenous species being 

 common to the near-by and older islands o£ 

 Cuba and Hayti, while many other species are 

 closely related to plants from these islands. 

 The chief agents in the introduction and dis- 

 tribution of the plant population are migra- 

 tory birds, supplemented by winds and ocean 

 currents. Notwithstanding the geologically 

 short period that the Bahamas have been above 

 the sea, they have witnessed the evolution of 

 niunerous species, there being many endemic 

 species known and many more which will be 

 made known as the result of the recent ex- 

 plorations. Many of these, it is believed, will 

 prove to be examples of rapid evolution (mu- 

 tation). 



Dr. Britton's observations were followed by 

 remarks on ' Collecting Algse in the Bahamas ' 

 by Dr. Marshall A. Howe. The shores of the 

 islands were said to offer a considerable variety 

 of physical conditions and to have a marine 

 flora which is on the whole varied and rich, 

 though apparently less so than that of the 

 Florida Keys. The shore lines are usually 

 rocky, but there are often stretches of white 

 sand which are nearly destitute of algse. The 

 tide rises and falls ordinarily from one to 

 four feet, but the withering effect of the sun- 

 shine is such that few species are found in the 

 strictly littoral zone except under shelving 

 rocks or where the shore is subject to an al- 

 most continuous spraying from the waves. A 



