THAT matter is discontinuous and consists of discrete particles is now an accepted fact, but it is by no means obvious to the senses. The surfaces of clean liquids, even under the most powerful micro0.001 mm Thinnest Wallaston Wire or Quartz Fibre.....' Eye ofN"S'Needle Influenza Bacilli, i ' I t i i i i i i i 1 J- Fig. i.-Cubes n to 15 compared with familiar objects to scale. scope, appear perfectly smooth, coherent, and continuous. The merest trace of a soluble dye will colour millions of times its volume of water. It is not surprising, therefore, that in the past there have arisen schools which believed that matter was quite continuous and infinitely divisible.