ANIMAL-PLANTS AND PLANT-ANIMALS. 681 



before briefly referred to, and which formerly were regarded as be- 

 longing to the animal kingdom — some species of algae. 



In 1843 the botanist linger, while examining certain green plant- 

 fibers under the microscope, suddenly noticed some sphere-like bodies 

 dart out of these fibers and move to and fro in the water, kept in 

 rapid motion through the aid of cilia. 



This wonderful sight (for up to this time nothing like it had been 

 observed) surprised him greatly, and he announced his discovery to his 

 collaborators in an essay bearing the title, " The Plant in the Act of 

 Transformation into an Animal." 



To the algae belong those minute organisms that sometimes give 

 to water a bluish-green color, that redden snow, and that change ordi- 

 nary rain into a rain of " blood." Ehrenberg states that the Red Sea 

 takes its name from the algae which it sometimes throws far up on its 

 shores. Reports of " blood-rains " are not at all infrequent in the rec- 

 ords of the past. Chinese history, written eleven hundred and fifty- 

 four years before the Christian era, makes mention of such a phenome- 

 non ; the Bible writers speak of similar occurrences, and Livy also 

 reports an event of this kind. 



But only one group of these organisms, the diatoms, will receive 

 our closer attention. They surpass the bacteria in size ; still, a good 

 microscope is needed to observe them. Whereas the bacteria present 

 only few, and at that, simple forms, but colors of varied hue, the re- 

 verse is true of the diatom family. Their color, when they possess 

 any, is a more or less dark brown or a green, but the delicacy and 

 beauty of their forms is striking. Some look like minute gondolas, 

 others resemble fans, or approach in form an S, a circle, or an ellipse. 

 If a higher magnifying power be employed, most dainty linear trac- 

 ings will be seen on their shells, for these beings are enveloped in 

 shells which consist chiefly of silica. 



Linne's expression, " Natura in minimis maxima'''' (with her 

 smallest agents Nature accomplishes her greatest works), is especially 

 borne out by the diatoms, for they have been active agents in the for- 

 mation of the crust of our globe ; rocks, ocean-beds, in short, entire 

 geological formations, are the results of their labors. The polishing- 

 slate of Bilin consists only of diatoms — one litre containing something 

 like two billions of them. A considerable part of Berlin, the capital 

 of the German Empire, is built upon a bed of diatoms, the uppermost 

 layer of which is still alive. 



Thus far we have noticed the power of locomotion — this prime 

 characteristic of animal life — only in the lower orders of plants, the 

 algae and fungi. Might we not expect to meet with this also in plants 

 of a higher order? Motion, perfectly free and unrestrained, we should 

 here of course seek in vain, but many plants possess the power of 

 moving some of their parts. In this connection we would recall 

 the Mimosa, which, in response to the slightest touch, will imme- 



