32 TECHNOLOGY OF THE DIATOMACE^. 



3rd. — The sediment resulting from this second operation 

 should be treated in the same manner, using filter No. 3, which 

 will usually, in the case of marine diatoms, give a final result ; 

 that is to say, that all the organisms contained in the soundings 

 will be found in the filter. 



The filter No. 4 need only be used if the mud contains very 

 minute species, and sufficiently interesting to call for its use, for 

 the work with this number is very slow and takes up a great deal 

 of time and patience, when a large quantity is to be operated upon. 



Extraction of Diatoms contained in the larger debris of 

 various kinds collected by the drags and nets. — The materials, 

 more or less bulky, collected by the drags and nets, ought to be 

 carefully tested ; whether fresh or dry matters little. You should 

 put apart the Algae, the Sponges (these ought to be themselves 

 divided into classes, as I have already shown),* the debris of 

 fishes and echinoderms, and, lastly, the stones composed of calca- 

 reous concretions, tubes of annelids, fragments of rock, etc. 



The preliminary washing of each of these different kinds 

 should be done separately, mixing ultimately those that appear 

 alike. 



I have indicated in previous numbers the course to be followed 



for the cleaning of Diatoms derived from Algae and from Sponges. 



The stones, if they are too large, must be broken up and treated 



as shells, etc. 



(To be continued.) 



M. Treby's studies of the planet Jupiter for the last thirteen 

 or fourteen years have satisfied him that the conditions existing 

 there are more stable than astronomers have of late years been 

 supposing. Even if the phenomena of the spots and bands are 

 atmospheric, their permanency and regularity point to some fixed 

 cause on the real surface of the planet controlling them. Besides 

 the " red spot/' which has now attracted attention for many years, 

 he finds permanent spots, even on the equatorial zone, having a 

 movement of rotation corresponding with that of this object. The 

 supposition may be legitimately drawn from this fact that this period 

 of rotation agrees with that of the planet itself 



* See this Journal, 111., Vol, iv. (1894), p. 307. 



