3?^ 



NATURE 



{July 1 8, 1878 



cold water, dissolve the contents of this vacuole. Keller 

 could not find this starch-like substance in Halisarca nor 

 Chondrosia, nor in any CalcispongicC. It seems desirable 

 in this connection to refer to the strictly granular condi- 

 tion in which chlorophyll appears in the case of Spongilla, 

 the granules having the form of concavo-convex discs. 

 In colourless (etiolated) specimens of Spongilla, the same 

 granules are present of a little different form, and as in 

 Neottia and other similar plants, these granules turn green 

 (develop into chlorophyll ?) on the addition of strong sul- 

 phuric acid(see Quarterly J ournal of Micros. Science, i^y^, 

 vol. xiv. page 400, where I have recorded these facts, and also 

 that of the occurrence of starch in Spongilla, though I 

 have not yet been able to find the authority for the latter 

 observation, which was made many years previously to 

 Keller's investigation). With regard to the question of 

 the formation of a gastrula in Sponges, and as to the 

 development of the endoderm of that gastrula into the 

 endoderm of the adult sponge, and therefore the con- 

 tinuity of the archenteric cavity of the gastrula with 

 the digestive cavity and canals of the sponge, Keller 

 has some remarks to offer which do not, in point of fact, 

 amount to very much. Like Franz Eilhard Schulze, 

 Keller fell into a complete error in his earlier publication 

 on the development of Calcareous Sponges. Haeckel, in 

 his monograph, stated that the sponge embryo was at 

 first a hollow one-cell-layered sac, on the inner wall of 

 which a second cell layer formed, by delamination, whilst 

 subsequently a mouth broke through. This was vehe- 

 menently denied and ridiculed by Metchnikoff ; it was also 

 denied by Oscar Schmidt, and by F. E Schulze, who 

 published a beautiful set of drawings showing that after 

 the embryo sponge had acquired some thirty or forty 

 cells, one hemisphere of cells became granular and 

 enlarged, and then invaginated — sunk into the other 

 hemisphere — thus forming a gastrula with endoderm and 

 archenteron by invagination. This account was at first 

 accepted as the true one, but it was strongly insisted upon 

 by Keller in his former memoir, that the orifice of 

 invagination closes up, as in fact the blastopore so 

 usually does throughout the animal kingdom, and 

 that the young sponge is then a mouthless closed 

 sac with two layers of cells. It was in this con- 

 dition that Haeckel saw it and described the further 

 stage in which the true mouth breaks through. There 

 is, however, still a great difficulty about the development 

 of the gastrula of sponges ; for no one can doubt, who 

 will examine a common calcareous sponge, or who looks 

 at Barrois' valuable memoir on the subject, that F. E. 

 Schulze was — as he himself has admitted — so far misled 

 in his account of the development of Sycandra raphanus 

 as to transpose two very important stages of the de- 

 velopment. In fact, the concavo-convex stage of the 

 embryo sponge, with one set of cells (endodermic) tucked 

 into the narrower, clearer, longer, ciliate cells, actually 

 precedes that in which the same cells form respectively a 

 hemisphere of clear ciliate cells and a hemisphere of 

 large swollen cells, not tucked into the former at all, but 

 so arranged that a small central cavity is closed in by 

 the two groups. How we pass from this stage to the 

 young sponge, or even to the two-cell-layered sac, is still 

 a complete mystery. One thing, however, is obvious. 

 Haeckel could hardly have been led to the generalisation 

 known as the gastrsea theory, which, on the whole, is a 

 truthful and productive generalisation, by erroneous 

 observation. We must, therefore, respect his positive 

 statements of fact. E. R. L. 



- T i» - _ 



GEOGRAPHICAL NOTES 

 The Swedish North-East Passage Expedition, under 

 Prof. Nordenskjold, was arranged to start from Tromsoe 

 about the isth inst. in the Vega, which sailed from Gothen- 

 burg about the beginning of the month. The Vega is com- 

 manded by Lieut. Palander, who was second in command 



of the Sofia in the polar expedition of 1868. Nordenskj old's 

 scientific staffconsistsof F.Kjellman, docentinthe Univer- 

 sity of Upsala, who took part in the expeditions of 1872-3 

 and 1875 j Dr. A. Stuxberg, who took part in the expe- 

 ditions of 1875 and 1876; Dr. E. Almquist, medical 

 officer J Andreas Hovgaard, lieutenant in the Danish- 

 navy, physicist ; and Giacomo Bove, lieutenant in the 

 Italian navy, hydrographer, the last-named officially sent 

 by his Government. The Vega is provisioned for two 

 years, but if the state of the ice be favourable, Nor- 

 denskjold hopes to reach Behring's Straits by the end of 

 September. The Vega will be accompanied as far as the 

 mouth of the Lena by a new steamer, the Lena, which 

 will ascend the river of the same name, on which it is 

 intended to ply, as far as the town of Yakoutsk. 



After an absence of several months Dr. Georg- 

 Schweinfurth returned to Cairo on June 13 from his 

 exploring journey through the Arabian desert. He 

 reports having crossed some fifty valleys in the desert 

 mountains, which he entered near Atfieh ; eventually he 

 reached Mount Gharib, and later on the Nile near Siut. 

 Dr. Schweinfurth intends returning to Europe for some 

 time to recruit his_ health, Avhich has considerably 

 suffered. 



Prof. Bastian, of Berlin, who has explored more or 

 less in nearly every region of the globe, is setting out 

 again for four years' work in Asia, and especially in 

 Further India, from whence he hopes to bring home 

 many additions to his already large ethnological collec- 

 tion. 



The long-talked-of voyage round the world, under the 

 auspices of the Secidtd des Voyages d' Etude, is at last 

 coming off under the leadership of Lieut. Biard. The 

 Jimon, the vessel in which the expedition sails, leaves 

 Marseilles this week. We have on several occasions 

 alluded to this and other similar projects, very tempting: 

 but much too expensive to attract many passengers. In 

 the present case only twenty-five student-passengers of 

 various nationahties have been obtained. The Junon 

 has on board three professors who will lecture on natural, 

 history, geography, physics, and meteorology. The ex- 

 pedition has been well planned, and if the programme is 

 carried out to even a moderate extent, the young voyagers 

 ought not only to enjoy themselves, but return with 

 much more knowledge, and perhaps wisdom, than when 

 they set out. The Jtatoti proceeds westwards to North 

 and South America, the archipelagos of the Pacific, Aus- 

 tralia, and New Zealand, China and Japan, India and 

 Egypt, returning to the Mediterranean by the Suez Canal, 

 A considerable part of the eleven months or so the 

 expedition is expected to be away will be passed in the 

 various countries at which the expedition will touch. 



In No. 3 of the Deutsche geo^raphische Blatter of the 

 Bremen Geographical Society Herr Camill Russ has a 

 long and valuable paper on the present position ot 

 Abyssinia ; the author has an intimate personal ac- 

 quaintance with the country. Dr. Sandeberg gives a 

 graphic and instructive account of a pilgrimage in 

 Russia, in the summer of 1876, to Solowjetsk, lying 

 between Lake Onega and the White Sea, and for cen- 

 turies one of the most celebrated places of pilgrimage in 

 Russia. Dr. Bretschneider, physician to the Russian" 

 Embassy in Pekin, sends a long letter, giving detailed 

 instructions as to the best methods and seasons for 

 travelling through Siberia and Mongolia to China, which' 

 will be found of great service to any enterprising tourist 

 who may have time and money enough to spare for such 

 an out-of-the-way journey. The letter conveys indirectly 

 a good deal of information concerning Siberia and 

 Mongolia. 



It is stated that the Lisbon Geographical Society 

 reports favourably on a project for an exploring expedi- 

 tion in Portuguese Guinea. 



