76 



Marvels of the Universe 



The method of procedure recommended by the expert in microscopic mounting, Martin J Cole, 

 is as follows : — " Take a piece of the rock not larger than a small marble, crush it and boil it in a 

 strong solution of washing soda. Strain off the hquid, retaining the sediment. Wash the sediment 

 several times, boil it in a test-tube containing nitric acid for about half an hour. This will remove 

 any trace of the carbonate of lime. Wash the sediment repeatedly in water to clear it of the nitric 

 acid." 



The sediment when dry is ready for mounting. Some microscopists heat the dried Polycystins 

 on a hot shovel in order to give the specimens a white opalescent appearance. They ma}' be mounted 

 on a dark background or as transparent objects are mounted. 



The specimens represented in the illustrations vary in diameter from the hundredth of an inch 

 to the two hundredth. Over three millions of them would occupy only a cubic inch of space ! 



The method just suggested of preparing and mounting collections or groups of Polycystins will 



POLYCYSTINS. 



In spite of their varied and graceful forms and delicate tracery, in actual size these Polycystins are like grains of fine sand. 



hold good for those which form the chief constituent of friable rocks, but many of the Jurassic 

 rocks, such as jasper, flint and chert, are too hard for treatment in this manner. It is necessary 

 with these more compact rocks to grind them down to the thinness which will render them 

 semi-translucent. 



A slice of rock so treated is fastened to a glass sHp by some transparent adhesive. Then 

 when a strong light is focussed on the under side of the slide the Polycystins will appear and will 

 make an attractive and valuable addition to the collection. 



One or two geologists will not admit that Polycystins are found in the Atlantic Ocean, or that 

 their range in Nature is so extensive as is commonly accepted ; but the late Thomas Rupert Jones, 

 F.R.S., one of the editors of the famous " Micrographic Dictionary," and an experienced geologist 

 and writer on geology, informs us that Ehrenberg found Polycystins in the Antarctic seas ; Bailey 

 described them from the depths of the Atlantic ; Miiller studied them from the Mediterranean, 

 Haeckel in the Adriatic, Wallich in the Indian Ocean ; Wyville Thomson, Carpenter and Gwyn 



