294 ROMANCE OF LOW LIFE AMONGST PLANTS. 



increase by division into two small round cells. By 

 far the greater number of them, when brought under 

 the microscope in a drop of water, remain at rest — 

 they lie close together in large numbers ; when they 

 are more dispersed in the fluid, they have a motion 

 which is not distinguishable from ordinary molecular 

 motion. When the drop of water moves they are 

 carried mechanically over the stage like other mole- 

 cules, and when this motion ceases they remain at 

 one spot in a sort of quivering state until a fresh 

 current carries them in another direction. If the eye 

 be kept carefully upon a part of the stage where the 

 small bodies are thinly dispersed, it will be observed 

 that they passively follow the current of the water, 

 nor, when the current has become sluggish, or has 

 even altogether ceased, are individual bodies ever 

 seen to detach themselves from the group and take 

 a contrary direction, which real monads would do 

 with great activity." 



Blood Rain. 



It is not always easy to determine from imperfect 

 description what is the precise organism which causes 

 the colour and gives rise to the phenomena of "blood- 

 rain." Ehrenberg discovered and described a minute 

 organism, which came to be called Ophidovionas sati- 

 gidnea, and, in more recent times. Spirillum sangiii- 

 neum, which has the credit of causing blood-rain (Fig. 

 58). It is one of the Schizomycetes, or minute beings 

 to which the Bacteria belong. " Like many other 

 plants, it readily passes from green to red. No one is 

 surprised by the green scum which covers reservoirs 



