August 2, 1900] 



NA TURE 



127 



in 



of the current and the voltage, to obtain photographs of the 

 tendons, and possibly the muscles ; for the photographs which I 

 have already obtained shosv great contrasts, and there are in- 

 dications of muscular layers and tendons. The contrast between 

 the bones and the flesh is extraordinary, much greater than in the 

 X-ray pictures usually obtained by the Rhumkorf coil. 



The investigator, by means of the liquid resistance, can keep 

 he lube at the same point of excitation. For the scientific 

 siudy of the X-rays nothing seems better adapted than this large 

 battery plant which I have had constructed, and it is not im- 

 possible that a smaller plant of the same number of cells, but 

 with less capacity, may be desirable for large hospitals. 



The first step in an investigation of the X-rays is to obtain a 

 steady source of these rays : one of the essentials for the accom- 

 plishment of this is a steady current which can be regulated. 

 This, I believe, I have secured. The next step will be the 

 roper control of the amount of gas in the tube. At one time 



believed that an oscillatory discharge was necessary for the 



ongest manifestation of the rays. My experiments, however, 



th a steady current have 

 ihown me that an oscillatory 

 discharge is not essential ; such 

 a discharge could not take place 

 through the large resistance 

 which I used — 4,000,000 ohms. 

 Such are some of the results 

 which can be obtained by the 

 use of this large battery. 



panied by Madame Weber-van Bosse, herself an accomplished 

 naturalist, who made a very complete collection of Algre during 

 the cruise, and who settled three very important points as a 

 result of the observations made, viz. : (i) the presence in un- 

 expected quantities of calcareous Algre (Lithothamnion) in the 

 Archipelago, so that they build up reefs of considerable dimen- 

 sions, in depths of 3 to 40 metres, in one case even at 120 metres. 

 Diflferent circumstances of level, current, &c., must co-operate 

 to render the occurrence of Lithothamnion in such quantities 

 possible : the expedition found them realised in at least thirty 

 different localities, and henceforth the possible contribution of 

 Lithothamnion-remains to the formation of the earth's crust will 

 in many cases have to be reconsidered by the geologists. (2) 

 The presence of a minute vegetal organism about which of late 

 years English and German naturalists have considerably differed 

 in opinion : the Coccosphrere. Neither the members of the 

 German Plankton nor those of the Valdivia expedition have 

 succeeded in satisfying themselves that the.se miniature spheres 

 with adherent discs of lime, already known in the Cretaceous 



P 



REIS VAN DE 5IB0GA 

 7 MAART iB99-27 FEBRUARI 1900 



'HE CRUISE AND 

 DEEP-SEA EXPLOR- 

 ATION OF THE 

 " SIBOGA " IN THE 

 INDIAN ARCHIPEL- 

 AGO. 

 'X'lIE annual summer meeting 

 ■'- of the Netherlands Zoologi- 

 cal Society, which was held in 

 Amsterdam on July i, was of 

 more than usual interest dn 

 account of the fact that it was 

 attended by all the members of 

 the scientific staff of the Siboga 

 expedition, who returned only 

 a few weeks before from their 

 one year's cruise in the different 

 basins of the Indian Archipelago, 

 during which they covered a 

 distance of about 12, coo sea 

 miles, i.e. about half the circum- 

 ference of the globe. The track, 

 as indicated on the accompany- 

 ing Fig. I, commenced at Soera- 

 baja on March 7, 1899 ; it ended 

 in the same port on February 27, 



1900. The vessel, which is a _ 



cruiser belonging to the Dutch 

 Royal Navy, was on its first trip, 

 and before its departure was 



specially fitted up for the work of the cruise, both with a sound- 

 ing apparatus of Le Blanc and of Lucas, with some 20 kilo- 

 metres of wire rope for dredging purposes, and with all modern 

 appliances for pelagic fishing, for plankton collection and for 

 deep-sea work (a " sondeur a clef" of the Prince of Monaco, 

 apparatus for obtaining sea-water from given depths according 

 to Petterson and Sigsbee, Hensen's nets, &c.) 



It may here be mentioned that very thorough experiments were 

 made with Mr. G. H. Fowler's net, which is specially intended 

 for plankton from given depths, and which can be opened and 

 shut at will at any moment. About this net, which is of very 

 recent invention, and which has as yet only been used by 

 Mr. Fowler himself, and perhaps on board the Valdivia, the 

 members of the Siboga expedition are very enthusiastic. It is 

 most trustworthy in its results and fruitful in its catches. 



The leader of the Siboga expedition, Prof. Max Weber of 

 Amsterdam, well-known by his former expeditions to. the East 

 Indies, to the far north and to South Africa, was accom- 



8IIPTE TOT 1000 MHER 

 - VAN lOCCW 2000 • 



saoo « 



Tiack of the Siboga. 



period and everywhere present on the bottom of the sea, are 

 organisms and not inorganic concretions or sediments. Mme. 

 Weber has now succeeded in demonstrating the truth of the 

 contrary, and has found this very lowly organised alga in preat 

 abundance, and entirely agrees with Mr. George Murray's 

 statements concerning the alga-nature of the coccospheres ; she 

 has even found in this alga green chromatophores, and has seen 

 phases of division of the spheres ; (3) the presence of shell- 

 and rock-perforating algas, a group hitherto neglected in the 

 tropics, of which she has brought home a great number. 



The zoological collections of the Siboga are very extensive, 

 both those collected on the coral-reefs and from the very 

 different depths. Deep-sea animals were met with at depths of 

 about 150 fathoms, where they would hardly have been ex- 

 pected, but where their presence is explained by certain 

 hydrographical circumstances to be mentioned later. Pori- 

 feia, and among them the most diverse Hexactinellids, were 

 exceedingly numerous. East of the Aru Islands, gigantic 



NO. 1605, VOL. 62] 



