132 Mr C. G. Ehrenberg's Observations on the 



pearance in France, examined it.>'more accurately, and thereby 

 opened a new field for investigation. He observed the water of a 

 pond to be of a brilliant red colour (rouge eclatant), the shade 

 of which was between cinnabar and carmine. It fortunately oc- 

 curred to him, not only to prove the colour of the water chemi- 

 cally, but also to observe it with the microscope ; and, as We- 

 ber discovered, he found that the cause of the colour was, in 

 animalculae, not visible to the naked eye. He took them for 

 a species of the volvox, having some affinity to the Volvox glo- 

 bator, but still very different. These are the first facts by 

 which we are informed that real infusoria could, in early times, 

 cause alarm among whole districts and communities. Girod 

 Chantran attempted to colour the magnified delineations of these 

 animalculas with their own bodies, using them as a pigment, and 

 was so enthusiastic about the beautiful and vivid colourj that he 

 recommended the preparation of them as a very lucrative specu- 

 lation, proposing that artificial lakes should be formed, capable 

 of being dried at pleasure, to obtain the valuable colouring 

 matter. No one had before raised the infusoria to so high a 

 political value. He calls this red infusory animal Volvox lacustris, 

 but has not described it more minutely. — Bullet, des. Sc. Nat. 

 de la Soc. Philomatique. a. 6. 



As every department of science has made great progress in 

 the 19th century, the knowledge of these appearances, and of 

 their various causes, has been greatly extended. 



Persoon examined a matter entirely similar to coagulated 

 bloodj that appeared on damp soil on road sides, and found that 

 it had a vegetable structure, and belonged to the species of 

 mushroom called Thelephora, on which account he, in 1801, 

 described it under the name of Thelephora sanguinea. Fries has 

 lately joined it with the (Thelephora) Phylacteria Crustacea, and 

 Agardh has more recently described it as an Alga, under the 

 name Palmella cruenta. 



The reddish salt-beds which Andreossy observed in the na- 

 tron lakes of Upper Egypt, are not so closely related to these 

 appearances, though I find them brought forward by Linck as 

 an instance of blood-red water. In my journey with Humboldt, 

 I saw a similar rose-red colour in the salt lake Elton, in the 

 steppe of Astracan ; it did not apparently belong to the water, 



