INFUSORIAL ANIMALCULES. 25 



momentary sparks. Some of these creatures are of considerable dimensions and 

 others barely visible, but a great proportion are entirely microscopic, and require 

 the aid of powerful instruments in order to perceive them and investigate their 

 forms and nature. 



The various species of Infusoria which illumine the ocean are extremely small 

 in size ; the largest do not exceed one-hundredth of an inch in extent, while the 

 least hardly attain the length of one twelve-hundredth of an inch. The phos- 

 phoric light emitted by these creatures is regarded by naturalists as the effect 

 of a vital action ; it appears as a single spark like that of the fire-fly, and can be 

 repeated in a similar manner at short intervals. 



COLORED TRACTS OF THE OCEAN. It has been noticed by navigators in all parts of 

 the sea, that extensive tracts of water are not unfrequently discolored at a great 

 distance from land. This change in the hue of the waves is caused by the presence 

 of minute marine animals and Infusoria, which impart their own tint to the waters 

 in which they abound, the far greater part being too small to be observed by the 

 naked eye. Nearly one-fourth of the Greenland sea, comprising an area of more 

 than twenty thousand square miles, is of a deep olive green hue. This coloring 

 matter was discovered by Mr. Scoresby to consist of animalcules, which crowded 

 the water in infinite numbers. On an average, sixty-four animalcules of one kind 

 were found in every cubic inch of water submitted to examination, and, on the 

 supposition that they were equally numerous throughout the body of colored 

 water, Mr. Scoresby computed, that a surface of two square miles, and fifteen hun- 

 dred feet deep, contained no less than twenty-three thousand millions of millions of 

 animalcules belonging to one species. And in order to form a more definite idea 

 of this vast multitude, he remarks that the number of years required for eighty 

 thousand persons to count them, would be equal to the period that has now elapsed 

 since the creation of the world. 



This green sea is described as the Polar pasture ground, the animalcules affording 

 an exhaustless supply of sustenance to creatures less minute, and these likewise 

 becoming the food of larger species, which in their turn are devoured by others of 

 greater size. And thus the series continues to increase until the waters are crowded 

 with numerous forms and types of animal life, the prey of the mighty monsters of 

 the deep, which in vast numbers resort to these prolific seas. 



On the east coast of Greenland Mr. Scoresby also met with broad patches and 

 bands of water of a yellowish-green color, as if sulphur had been strewn upon 

 the waves ; and upon examining it with a microscope it was found swarming with 

 animalcules. Most of them were of a globular form and of a lemon color, and 

 seemed to be possessed of little activity, but the rest were in constant motion. So 

 small were these creatures that the largest did not exceed the two-thousandth of 

 an inch in length, and many of them were but half this size. A single drop of the 

 water, and that not the most discolored, was found to contain more than twenty-six 

 thousand animalcules. The glass upon which the drop was placed for examination 

 was ruled into small squares of equal size. The drop, when magnified linearly one 

 hundred and sixty-eight times, covered five hundred and twenty-nine of these 

 squares; and in every square, on an average, fifty animalcules were found; which 

 made an aggregate of twenty-six thousand four hundred and fifty. Mr. Scoresby 

 computed that in a tumbler of water one hundred and fifty millions of these animal- 

 cules would find ample room, and regarding each as one- four-thousandth of an iucli 



