THE LOWER FOBMS OF LIFE. 47 



This is the simplest form of Orbitolites ; there are others 

 found in large quantities in the dredgings on the coast of 

 Australia, in which the structure is much more complex. It does 

 not enter into my plan to give details of these forms. I have said 

 enough to give a general idea of how the Foraminifera are con- 

 structed. There is a great deal of most interesting matter contained 

 in Drs. Williamson and Carpenter's splendid works before mentioned, 

 and to them I must refer those who wish to extend their studies 

 of these lowly forms of life. The student has one advantage not 

 attained in the Protozoons I have previously dealt with, viz., the 

 Foraminifera are many of them large enough to be picked off sea- 

 weed or out of sea-sand, with the aid of a moderate lens, and 

 preserved in our cabinets for examination. But they will not be 

 found in any number on the shore. They live in deep water, and 

 sand or weeds for examination must be obtained in two or three 

 fathoms. The following is Dr. Williamson's directions for securing 

 specimens : " If the collector merely seeks dried shells for his 

 cabinet, indifferent whether living or dead, the process of floating 

 them is by far the most productive. A few pints of the sand must 

 be collected from beneath at least two or three fathoms of water, and 

 thoroughly dried ; it should then be passed through a conchologist's 

 sieve, or coarse net, so as to eliminate all the rough material. The 

 finer portions passed through the sieve must be poured into a bowl 

 containing cold water, and well stirred up, so that the whole may be 

 saturated. On being allowed to stand a few moments the more 

 delicate of the concamerated shells, rendered buoyant by the air 

 contained within their chambers, readily float to the surface, while 

 the sand and mud settle to the bottom. (Be careful at this stage to 

 burst all air bubbles on the surface.) A little manipulation enables 

 the collector to blow off this scum so rich in treasures, and the 

 addition of fresh water cleans them ; the creaming of the bowl 

 being repeated as long as any sediment or impurity remains. The 

 water may be now drawn off by a syphon, and the objects dried, 

 when they are easily collected for examination." 



Dr. Williamson carries this process a step further, in order to get 

 the cleanest specimens. Sweeping the sides of the bowl with his 

 forefinger, he transfers them to a small evaporating dish, and boils 

 them in liquor potassae over a spirit lamp for some moments, 

 thus dissolving organic matter, and leaving the shells free from 

 impurity. The solution must now be poured off, and the shells, 

 which sink to the bottom, washed in cold water, and again dried for 

 examination. 



When, however, the specimens are wanted living, Dr. Wil- 

 liamson points out that the mode of collecting them must be 



