INFUSORIAL ANIMALCULES. 



39 



yellowish green color, and varies in length from one-four teen hundred and fortieth 

 of an inch to one-Jive hundred and seventieth. It is quite common, and is found 

 both in a living and fossil condition. 



THE ZIGZAG ANIMALCULES. Figure 45 is a drawing 

 of a common Zigzag animalcule, found by Dr. Mantell 

 in the neighborhood of London. These Infusoria have 

 received the above appellation in consequence of their 

 being developed in zigzag chains, each link consisting of a living creature. This 

 mode of union arises from the circumstance, that although the shells of all the 

 animalcules are perfectly separated, their bodies are not, and thus remaining at- 

 tached, they present to view an irregular series, such as is displayed in the figure. 

 The flinty shell is three or four times as long as it is broad, is prismatic in shape, 

 and contains thirteen cross lines in every twelve hundredth of an inch. A nar- 

 row opening runs from one end of the shell to the other, through which soft, 

 fleshy members are protruded, by the aid of which locomotion is effected. The 

 natural size of each shell of the chain in the engraving, is one-four hundred and 

 thirty-second part of an inch. \ 



In figure 46, is shown a cluster of another species of 

 these animalcules, which, when imperfectly divided, are 

 attached side by side, and slide one upon the other the 

 entire group shortening and lengthening itself at plea- 

 sure. Their color is of an orange yellow, and their 

 length varies from one- two hundred and fortieth of an 

 inch to one-eleven hundredth. 



THE PALM, FAN-SHAPED ANIMALCULE. A species of Infusoria belonging to 



Fig. 46. 



of 



the Bacillaria and bearing 

 is shown in figure 47. 



the family 

 the above name, 



These animalcules are encased in a shell 

 which is broad and wedge-shaped, and 

 form a fan-like cluster, rising from a single 

 trunk or stalk. The stalk is produced by an 

 excretion of the animalcule, and is not pos- 

 sessed of any vital power : for if the branch- 

 ing, living groups are broken off, no fresh 

 buds, teeming with animal life, are put forth 

 from the mutilated trunk, but it soon crum- 

 bles away and utterly perishes. This ani- 

 malcule increases by a longitudinal self-divi- 

 sion, but the separation does not extend to 

 the stalk ; for this remains entire while the 

 creature continues to develope in fan-shaped 

 groups, the trunk branching into thick ge- 

 latinous boughs, to which the separate ani- 



Fig. 47. 



Fig. 48. 



