RHIZOPODA FORAMINIFERA. 79 



cavity, but although they have neither mouth nor stomach, yet, 

 according to Professor KolUker, and as has been mentioned 

 before, they take in soUd nutriment, and reject what is indigestible. 

 When in its progress through the water one of these minute organisms 

 approaches one of the equally minute Algse, from which it draws 

 nourishment, it seizes the plant with its pseudopods, and gradually 

 encloses it on all sides ; the pseudopods, to all appearance, be- 

 coming more or less shortened in the process. In this "way the 

 captive is brought close to the surface of the body ; a cavity is 

 apparently then formed, in which the prey is lodged, which closes 

 round it on all sides. In this situation it is gradually drawn towards 

 the centre, and passes at last entirely into the mass, when the 

 engulfed morsel is gradually dissolved and digested. 



Reticulosa, or Foraminifera. 



What, then, is a Foraminifer? It is a very small calcareous shell 

 nearly invisible to the naked eye ; for, in general, its dimensions 

 range between '005 to "050 of an inch in length. Examine under a 

 microscope the sand of the ocean, and it will be found that one-half of 

 it consists of the de'bris of minute shells, of various but well-defined 

 forms, each pierced with a number of holes. To this they are 

 indebted for their name Foraminifera, from forameti, a hole. With 

 these microscopic animals Nature has worked wonders in geological 

 times ; nor have the wonders ceased in our days. 



The sand of the littoral zone of all existing seas is so full of these 

 minute but elegant shells, that it is often nearly one half composed 

 of them. Ehrenberg, the celebrated German microscopist, was 

 recently invited by the Prussian Government to assist in tracing the 

 robbery of a special case of wine. It had been re-packed in littoral 

 sand only found in an ancient sea-board in Germany. The criminal 

 was thus detected. M. d'Orbigny found in three grammes (forty- 

 six grains troy) of sand from the Antilles, 440,000 shells of Fora- 

 minifera. Bianchi found in thirty grammes (467 grains) from the 

 Adriatic, 6,000 of these shells. If we calculate from these facts 

 the proportion of these beings contained in a cubic metre alone of 

 sea-sand, we reach a figure which passes all conception. What would 

 this be if we could extend the calculation to the immensity of surface 

 covered by the waves which surround the globe ? 



M. d'Orbigny has satisfied himself, by microscopic examination of 

 sands from all parts of the globe, that it is the de'bris of Foraminifera 

 along witli the sea-sand, which form, in all existing seas, those 



