Jan. lo, 1889] 



NATURE 



259 



GEOGRAPHICAL NOTES. 

 Ar the Koyal Geographical Sxiety on Monday night, a 

 per was read by Mr. F. S. Arnot on his journey from Natal 

 I>ihe and Benguella, and i hence across the central plateau of 

 !i ica to (lie sources of the Zambesi and the Congo. Mr. Arnot 

 icached Nat.d in September 1881, and has only just returned 

 from his seven years' wanderings, during which he crossed the 

 continent to some extent in the route of Livingstone. His 

 paper forms an important supplement to the work of Living- 

 stone, Cameron, Ivens and (Japello, and the German traveller 

 Reichart. Crossing from Natal obliquely, he struck the Zambesi 

 near Sesheke, and ascended the river to Lealui, the town of 

 Liwanika, to endeavour to persuade the chief to let him proceed 

 northwards among the Batonge and Mashashe. Unsuccessful in 

 this, Mr; Arnot left Lealui in May 1884, and proceeded to Bihe 

 and the coast. Returning to Bihe, Mr. Arnot proceeded east- 

 wards, crossing the interesting country from which so many 

 rivers take their rise, flowing north, south, and west, to the 

 Congo, the Zambesi, and the Atlantic. He touched Lake 

 Dilolo, which he has reduced to very small dimensions, and has 

 done something to rectify our knowledge of the sources of the 

 Zambesi. The main stream, according to Mr. Arnot, comes 

 from the east, and cf this the Leeba is only a tributary. He 

 stayed for two years at the capital of the kingdom of the chief 

 Msidi, of whom and his government he gives an interesting 

 account. Here he was in the region of the sources of the 

 Lualaba. Msidi, who is really a native of Unyanyembe, seems 

 a man of some ability, and is rapidly extending his power. He 

 and Kangombe between them have almost swallowed up the 

 once powerful kingdom of Muata Vanvo. Mr. Arnot returns to 

 the Bangweolo region in March next. 



Dr. Meyer, and his companion Dr- O. Baumann, who were 

 recently compelled by the hostility of the natives in East Africa 

 to take flight to the coast, actually succeeded in crossing the 

 country of Usambara by a new route. After marching through 

 Bondei to the mission station of Magila, they travelled for 

 several days through a fertile, and in places thickly-wooded de- 

 pression, which forms part of the Sigi basin, reaching Hanon on 

 September S. Crossing the Mielo Ridge they descended into the 

 valley of the Kumba River, and on September 18 reached the 

 valley of Mlali, where the Umba River runs. This region is 

 well cultivated, and covered with numerous and large villages. 

 Proceeding to Masende, Dr. Baumann with some natives ex- 

 plored the mountains, arriving eventually at a fertile region 

 inhabited by the Wambunga. These people differ completely 

 from the Washamba of Usambara, and are a remnant of the 

 aborigines of the mountains, speaking a dialect similar to the 

 Kipare. 



From the new volume of the Geographischc Jalirbuch we 

 leani that there are now loi Geographical Societies in the 

 world. Of these, France and her colonies have more than any 

 other country, — 29, with 19,800 members ; next comes Germany, 

 with 22 Societies, and 9200 members ; followed by Great 

 Britain and her colonies with 9 Societies, and 5600 members. 

 There are altogether 130 geographical serials published in the 

 various countries of the world. 



M. Jean Chafkanjon, the explorer of the Orinoco, we learn 

 from the Scotlish Geographical Magazine, is about to undertake 

 a new task. He is going to explore the peninsula and lake of 

 Maracaibo. A tribe of Indians live in the peninsula, concerning 

 whom no scientific data have been obtained, for they allow no 

 one to go among them. M. Chaffanjon will try to penetrate 

 this mystery. He will also examine the lacustrine dwellings of an 

 extinct race in the Maracaibo Lake, and then, following the 

 chain of the Andes, will ascend to the source of the Magdalena, 

 cross the group of mountains which separates this river from the 

 Rio Canca, and explore the latter down to Antioquia. 



SOME ANNELIDAN AFFINITIES 

 IN THE ONTOGENY OF THE VERTEBRATE 



I NERVOUS SYSTEM. 



I T N the controversy respecting the ancestry of the Vertebrata 

 \ ■*■ the nervous system has always played an important part : 

 that system is — I think Prof. Wiedersheim was the first to say it 

 — the most aristocratic and conservative of all the orj^'an systems 

 of the animal body, and it clings to ancestral traditions more 

 than any other. Anyone who has read Kleinenberg's marvellous I 



account of the complicated manner in which the permanent 

 nervous apparatus of the Annelid worm is built up from that of 

 the larva (in which process of building up it passes through 

 stages which can only be looked upon as ancestral), will readily 

 agree that if we are ever to trace the ancestry of Vertebrates 

 at all, the nervous system will probably form a significant factor 

 in the solution. 



The attempts made hitherto to homologize the nervous system 

 of Vertebrates, either in the embryo or in the adult, with that of 

 some Invertebrate or other, do not appear to have met with much 

 success. To take one of the most recent of these. Prof. Hubrecht 

 has, at the close of his Challenger Report on the Nemertijies, indi- 

 cated what he would regard as ]>oints of homology between the 

 nervous system of this group and that of Vertebrates. The com 

 parison is, in my opinion, exceedingly strained, and indeed it 

 would not be difficult to show that it is absolutely erroneous. 



The theory of the descent of Vertebrates from animals allied 

 to the Tunicata was, as is well known, partially based on 

 certain characters of the nervous system in the Tunicate larva ; 

 but that theory can now hardly be defended, since Dohrn has 

 adduced powerful arguments for putting the descent the other 

 way about — i.e. from Vertebrates to Tunicata — by insisting that 

 the structure and development of Tunicata prove them to be 

 degenerate Vertebrates. 



As a third alternative we have a descent offered us by Bateson 

 from Balanoglossus-like animals, with gill-clefts and a nervous 

 system and notochord resembling that of Vertebrates. Many 

 zoologists see the main and only resemblance between Balano- 

 glossus and Vertebrates in the possession of gill-clefts. It is many 

 years now since these structures in the two groups were first com- 

 pared, and the supposed relationships between them more recently 

 insisted upon do not seem to me to be of a very stable order. 

 The nervous system and notochord of Balanoglossus are to be 

 excluded from the comparison simply because they are on the 

 haemal side of the body, and therefore cannot be compared to 

 structures which, like the nervous system and notochord of Verte- 

 brates, are tiol on the haemal side. As I am here only consider- 

 ing the claims of the nervous system to an homology, I cannot 

 fully di'cuss the gill- clefts of Balanoglossus, and need only 

 remark that a respiratory function of some part of the alimentaty 

 canal — generally the anterior part — is very commonly met with 

 in many classes of the animal kingdom. Now, gill-clefts alone, 

 without sense-organs, skeleton, nerves, or muscles (and these have 

 not been described yet for Balanoglossus), are merely the results 

 of a gut respiration, the alimentary tract having acquired 

 openings on the lateral surface of the body, and it is by no 

 means improbable that such openings could be acquired inde- 

 pendently in two groups of animals otherwise widely separated. 

 Two such groups are Balanoglossus and the Vertebrata. 



The only remaining theory ^ of Vertebrate ancestry demand- 

 ing consideration is that of Semper and Dohrn, which would 

 derive those animals from Annelid worms. The first com- 

 parisoA concerned the nephridia ; and it is to be remarked that 

 the nervous system, the question of the homology of which has 

 not been left in the background, has always been the great 

 obstacle in the w ay of its acceptation, for no one has, as yet, 

 succeeded in finding, in the Vertebrate, any homologue of the 

 Annelidan supra-oesophageal ganglion. There have been plenty 

 of wild and improbable speculations as to its whereabouts. A 

 new era, however, opens with Kleinenberg's hint that possibly 

 the supra-oesophageal ganglion of Annelids is suppressed even in 

 the ontogeny of Vertebrates ; and, if we concede this, we must 

 look to the ventral chain of the Annelids as typifying the initial 

 structure from which the central nervous system of Vertebrates 

 arose. And now what points of agreement have been discovered 

 between these two structures and their related nerves and sense- 

 organs ? 



Eisig has compared the lateral sense-organs of Capitellida;, 

 which are segmentally arranged along the whole body of the 

 animal, with the lateral sense-organs of Vertebrates. The latter 

 arise in the head, and are at first confined to the head meta- 

 meres : later they grow on to the trunk ; they there become also 

 segmental, but they are innervated by a true cranial nerve. 

 Now, although Dr. Eisig's comparison is a very enticing one, it 

 can be neither accepted nor rejected without further inquiry. 

 There are many facts for it and some very important ones 

 which, though not directly opposed to it, are not in its favour. 

 We must attach a good deal of importance to it, for the 



' Balfcur (" Elaimobtanch Fishes." p. 171) tnunciatcda different theory 

 which can l.ardly now be maintained, _ 



