36 



VIEWS OF THE MICROSCOPIC WORLD. 



THE RUST-LIKE GALLIONELLA. In figures 31 and 32 are shown several deli- 

 Fig si Fi 3 cate an( ^ branching chains, composed of these little beings, 

 ""which, from the resemblance of their color to that of iron-rust, 

 have received the name of Rust-like Gallionella. Each of these 

 Infusoria is invested with a flinty shell, of an oval shape, round- 

 ed at both ends and smooth on the surface. They are found in 

 most of the waters impregnated with iron, and also in peat- 

 j-J water, which contains a little of this mineral. Every thing 

 beneath the surface is covered by these creatures in countless 

 numbers, forming, by their union, a light mass composed of 

 such delicate flakes, that it is dispersed by the slightest motion. 

 In the spring, this flocculent substance consists of short chains 

 of pale-yellow globules, strung together like rows of beads, which can be readily 

 separated from each other. Their union, however, is detected with difficulty at 

 this time ; but as the season advances, the Infusoria become more developed, and 

 their structure is better discerned : when summer arrives, the threads and chains 

 of which the whole mass is woven, yield to the power of the microscope, and the 

 texture is more clearly revealed to the eye. At this period, the color of this 

 animalcule is of a deep rusty-red ; but in the spring, its tint is that of a 

 pale-yellow ochre. This species of Infusoria is found both in a recent and fossil 

 state, and measures only one-twelve thousandth of an inch in diameter. 



THE NAVICULA, OR LITTLE-SHIP ANIMALCULES. This kind of Infusoria belongs 

 to the Bacillaria, and is shaped like a boat or ship, and from this resemblance 

 has received the name of Navicula, which in the Latin language signifies a little 

 ship. They are never united like the Gallionella, in chains ; but exist singly and 

 in pairs, enclosed in a durable, thin, siliceous shell, generally four-sided, and 

 which, when slightly pressed, divides either into two or four parts, disclosing 

 the appearance of ribs running across it. A jelly-like substance, which con- 

 stitutes the body of the animal, occupies the interior of the shell, and portions 

 of matter, of a green, yellow, and brown color are here perceived, which have 

 been regarded by naturalists as the eggs of the Navicula. Many of the ship- 

 animalcules propagate by self-division in the two directions of their length and 

 breadth ; the separation commencing in the soft body beneath the shell, which 

 afterwards divides into parts corresponding to those of the body. Twenty-four 

 different kinds of fossil Navicula have been discovered, fourteen of which have 

 been identified with species now living. 



GREEN NAVICULA. Figure 33 is a drawing of this animalcule, representing 

 a specimen taken by Dr. Mantell from a pool in Clapham Common, in the vicinity 



of London. The small dots are the stom- 

 ach-cells of the creature, and the rib-like 

 divisions of the shell are distinctly seen 

 throughout its whole extent. So numerous 



Fiff 33 



