BY ARTIFICIAL MEANS. 363 



what are the phenomena they present at the moment when the 

 Diatoms succumb to their action. 



It is often preferable to fill the cells with the liquid and a trace 

 of deposit from a culture. By this means you obtain very quickly 

 a very flourishing growth in the cell, identical with that which has 

 been going on in the mother liquid. 



The movement of Diatoms is, in some cases, very difficult to 

 observe for a length of time. This is an inconvenience to which it 

 is, and probably always will be, difficult to apply a remedy ; but the 

 diatomist ought to esteem it a fortunate thing that the algse that 

 are the objects of especial study have movement infinitely less 

 lively than the Protozoa, the study of which, thanks to the labours 

 of Balbiani and of Biitschli, is nevertheless at the present time in 

 an advanced stage. 



Chapter IV. 

 THE FUTURE OF THE CULTURE OF DIATOMS. 



FROM the commencement of this series of articles, I had the 

 intention to recapitulate the principal facts that the culture 

 of Diatoms has revealed to the observer ; but in proportion 

 as I have advanced in these studies, the field, at first relatively 

 narrow, has widened so rapidly that I have been obliged to pre- 

 serve in another publication,''^ in numerous paragraphs, the interest- 

 ing remarks that the cultures in question have enabled me to note. 

 I have therefore thought that it will be more profitable for the 

 readers of this Journal to find in the special monographs the facts 

 that contribute to the history of such and such Diatoms, and to 

 read the general conclusions, in which all the interest resides, 

 especially in the exposition of what has gone before. 



I prefer to give, in broad features, in the lines that follow, 

 some special methods of investigation, pointing out the ends that 

 may be attained. In thus acting I believe I shall do more useful 

 work, more profitable to the science of the siliceous Pheophyces 

 than in the enumeration of the general properties of these algae ; 

 a kind of abridged edition of the labours that I have already pub- 

 lished and of those to which I have consecrated these numerous 

 pages. 



* A /males de JMicrographe^ Tome iv., 1892. 



