United States or Kuwait ? Vote for the TOP Country of the Week !
If we look through the microscope at a drop of water containing living arcellae, we may happen to see one of them lying on its back at the bottom of the drop, and making fruitless efforts for two or three minutes to lay hold of some fixed point by means of a pseudopodium.
When this has been obtained, the air disappears without our being able to discover any other reason for its disappearance than the fact that it is no longer needed. . . . If we bear these circumstances in mind, we can almost always tell whether an arcella will develop air-vesicles or no; and if it has already developed them, we can tell whether they will increase or diminish . . . The arcellae, in fact, in this power of altering their specific gravity possess a mechanism for raising themselves to the top of the water, or lowering themselves to the bottom at will.
Word Of The Day