April 7, 1899.] 



SCIENCE. 



501 



of individuals are accustomed to go for a 

 certain portion or season of the year, most 

 commonly for a vacation period in accord- 

 ance with which they are denominated 

 summer or winter laboratories. The larger 

 number of the investigators tends towards 

 securing a more complete idea of the bio- 

 logical problem as a whole, so that the re- 

 sults obtained from such stations are of 

 evident value. Yet, at the same time, it 

 must be noted that they are distinctlj^ in- 

 ferior, even to many individu.al resorts, since 

 during the larger portion of the year no in- 

 vestigations are carried on and the results 

 obtained are necessarily partial and incom- 

 plete in their character, and hence unavail- 

 able for the decision of the broader and more 

 fundamental biological questions. 



Permanent stations are those at which 

 operations are conducted throughout the 

 entire year by a definite corps of observers. 

 The continuity of their work renders their 

 results valuable for the decision of general 

 biological problems, and, at the same time, 

 the permanent force which, in part, at least, 

 is indispensable in such an institution, im- 

 plies that the undivided attention of the 

 observer is devoted to these problems; from 

 this we may then expect justlj^ that greater 

 results will be obtained than in the case 

 even of the best of individual resorts, since 

 the investigators who are carying on opera- 

 tions at these are, so far as I know, without 

 exception, connected with educational or 

 scientific institutions which demand at least 

 a part of their time, and to that extent di- 

 vide their interest and their energy. 



It is furthermore clear from what has 

 been previously said that such permanent 

 stations are of two distinct classes. First, 

 those which may be denominated general, 

 even though their work is of the greatest 

 value for special p>urposes, and second, those 

 which are distinctively technical by virtue 

 of their association with specific enterprises. 



It is but natural that the different conti- 



nents are very unequally represented with 

 regard to the number of stations that have 

 been established upon them, and with re- 

 spect to the knowledge that has been gained 

 in reference to their fresh-water fauna and 

 flora. Thus, our knowledge of the Aus- 

 tralian fresh-water fauna is confined, at pres- 

 ent, to the report of collections made by 

 travelers, and to the investigation of speci- 

 mens raised by Sars from dry mud which 

 had been sent to him. Of Africa we know 

 that fifteen years ago an expedition brought 

 word from Lake Tanganyika that while 

 rowing across its waters they encountered 

 swarms of jelly-fish, while many of the 

 gastropod shells which were brought back 

 with them showed, in an equally striking 

 way, their marine character. These reports 

 have been confirmed by an expedition that 

 has just returned, and the strikingly ma- 

 rine complexion of the fauna of the lake 

 can hardly be doubted. This appears all 

 the more strange since collections made at 

 Lake Nyassa, which lies decidedly nearer 

 the sea, show nothing but what is specif- 

 ically lacustrine. Such facts point, of 

 course, to the importance of the African 

 fresh-water stations of the future. 



From various lakes of Asia, all the way 

 from Ceylon to Siberia, numerous more or 

 less extensive collections have been made 

 by travelers, though there is hardly any- 

 thing sufficiently extended to warrant the 

 statement that a station has been located, 

 even for a limited time, at any point, espe- 

 cially since the collections have not been 

 investigated by men who had made them, 

 but have been turned over as alcoholic ma- 

 terial to European investigators for study. 

 We do know, however, that Lake Baikal, 

 which is situated almost in the center of 

 the continent, harbors a rich molluscan and 

 crustacean fauna that is characteristically 

 marine in its form, and is further distin- 

 guished by possessing many sponges clearly 

 of marine type, and at least one species of 



