LIBRARY 

 NEW YORK 

 J O U E N A Li iBOTANiCAt 



GARDEN 



ROYAL MIOROSCOPIOAL SOCIETY. 



AUGUST 1884. 



TKANSACTIONS OF THE SOCIETY. 



XI. — Researches on the Structure of the Cell-ivalls of Diatoms * 

 By Dr. J. H. L. Flogel. 



CRead 12th December, 1883.) 

 Plates VIII. and IX. 



The various objections made to my previous researches have induced 

 me to undertake a re-investigation, and although this has for the 

 most part been simply corroborative, it has appeared to me desirable 

 to publish the results, together with some obtained in reference to 

 other diatoms of which only preliminary communications (7) have 

 hitherto been published. 



Day by day the old erroneous views on the structure of diatoms 

 are repeated in the text-books of Botany, and nobody seems to have 

 approached the subject seriously ; the present paper may therefore, 

 I hope, arouse sufficient interest to induce further investigation. 



I. Method of Investigation. 



I have already (6) described the methods which I have followed 

 in the investigation of Pleurosigma ; but it is necessary to refer 

 here to the method of section-cutting. In applying my greater 

 experience to Pleurosigma and other diatoms I have obtained 

 generally much better results than formerly, which have lent addi- 

 tional confirmation to my paper of 1870. 



Time of making Sections. — Accidentally I made my original 

 investigations during the summer. When in the winter I wanted 

 to replace some preparations, I found it impossible to obtain success- 

 ful results. The cause was the artificially heated room. It is 

 useless to attempt to bring the gum to the right degree of hardness 

 by the addition of glycerin, sugar, &c., as, in consequence of the 



* The original paper is written in German, and has been translated by 

 Mr. J. Mayalljun. 



•SfT. 2.— Vol.. IV. 2 M 



