PROTOPHYTKS. 



31 



Figure 19 is a magnified portion of a cluster, and dis- 

 plays the manner in which these slender filaments are 

 connected with the common covering. The length of a 

 single organism of this kind, without its filament, is one 

 seventeen-hundredth of an inch; and the size of a cluster 

 varies from one one-hundred-and-ninetieth part of an inch 

 to one two-hundred-and-eightieth. 



THE BLOOD-LIKE ASTATIA. This plantule belongs to a kind which has received 

 the name of Astalia,* from the circumstance that they have no fixed abode like 

 the volvox monads, but are endowed with a perfect freedom of motion. They 

 have the power of changing their form at pleasure, are destitute of an eye-speck, 

 and move from place to place by means of a tail, and a delicate, vibrating cilium. 

 These curious atoms are sometimes produced in such vast numbers as to dye the 

 waters in which they live with a crimson hue. 



The blood-like Astatia is delineated in figure 20. Its 

 body, when extended, is spindle-shaped, as there exhibited ; 

 at first it appears of a green hue, but afterwards assumes 

 a blood-red color. Figure 21 shows an individual of the 

 same species with the body contracted. The length of this 

 little organism is one three-hundred-and-eightieth of an 

 inch. 



Fig. 21. 



THE BLOOD-RED EUGLENA. The Euglena is a variety of the Astatia, but differs 

 from it in possessing a beautiful red eye-speck. It varies in length from one two- 

 hnndred-and-fortieth to one three-hundredth of an inch, and is of an oblong shape ; 

 but is capable of changing its appearance. This curious characteristic is recognized 

 in figures 22, 23, and 24, where the organism is delineated under the various 



Fig. 20. 



Fig. 22. 



Pig. 23. 



Fig. 24. 



shapes it assumes. During the early stages of its existence its color is green ; but 

 upon arriving at maturity it is of a blood-red hue. Individuals are seen, however, 

 partaking of both hues, being variegated with red and green spots. The Euglena 

 moves through the water with a slow motion, by the aid of a thread-like cilium, 

 which is seen in figure 23 ; and the currents produced by this organ, and which 

 are discernible when the water is colored, are delineated in figure 22. In figure 

 24, where the cilium appears double, the plantule is on the point of dividing into 

 two, and a single cilium belongs to each of these parts which are soon to become 



* Greek, a, privative, without ; stasis, a station, hence Astatia. 



