PART OF DIATOM CASE (PLEUROSIGMA ANGULATUM) 



Magnified 4,900 diams. 



From a photo-micrograph by Dr. R. Zeiss 



Reproduced by permission of Messrs. C. Zeiss and Co. and Messrs. J. and A. 

 Churchill, publishers of Carpenters "The Microscope" 



Face page 156 



