THE MICROSCOPE. 



NOVEMBER, 1893. 



Number 11. 



New Series. 



OBJECTS SEEN UNDER THE MICROSCOPE. 

 III. — Nature's Jewels (Diatoms). 



[PHOTO-MICROGRAPH.] 



The Diatom here presented is the Stirirella gemma. There are 

 nearly 60 species of the genus Surirella. This is a marine form 

 and measures about 1-240 of an inch in length. The cut shows 

 an enlargement of 1200 times. 



This photo-micrograph was made by Nachet of Paris by 

 means of a 1-10 oil immersion objective, and the bringing out of 

 the minute pearls is considered a great feat. They are shown 

 somewhat better in his original than in this engraving. Nachet 

 is perhaps the best maker of microscopes in France. 



To those unfamiliar with diatoms, we may say that this very 

 minute form is a plant, whose shell naturalists call a frustule. 

 The soft parts, when present, more easily disappear leaving the 

 frustule in sight. The illustration presents a side view of a frus- 

 tule unaccompanied by any soft parts. A front view would be 

 of quite different shape and an end view still more so but of less 

 interest. This hollow frustule consists of two halves called 



