OF THE ASTASIiEA OK EUGLEN^A. 539 



Dinema. Again, Schneider (A. N. II. 1854, xiv. p. 327) would separate 

 Chlorogonium from the Astasiaea on account of its unchangeable form, and Mr. 

 Carter {A. N. H. 1856, x\iii. p. 116, and 1859, iii. p. 15) would refer Euglence 

 to the vegetable, and Astasice to the animal kingdom. The differences pre- 

 vailing among natm^ahsts relative to the beings to be admitted into the family 

 Astasiaea indicate either that its characters are not laid down with sufficient 

 precision, or that it is not a natural group. The power to vary the figure 

 can be no adequate character ; for this is partaken by the gonidia of various 

 Algae in certain amoebiform stages of existence, and, on the other hand, is 

 absent in some species enumerated by Ehrenberg in the genus EugJena, as 

 well as in Chlorogonium. The tapering or tail-like prolongation of one ex- 

 tremity, the existence of one, two, or more ciliary filaments, as also of a red 

 speck, are likewise features common to numerous zoospores. Even when 

 appeal is made to their internal organization and functions, nothing appears 

 whereon the definite characters of a natural family can be built. Eor, on the 

 one hand, the organization assigned them by Ehrenberg is now held to be 

 untenable, and, on the other, no harmony prevails resj^ecting the internal 

 structure as recorded by different observers of the various genera. Mr. 

 Carter, in the paper just quoted, states unhesitatingly that most of the 

 Astasia enumerated by Ehrenberg are animal forms, whilst the Eiigleme 

 are vegetable. He remarks that, " although no two Infusoria can be more 

 alike than Astasia limpida and Euglena when casually observed .... yet the 

 absence of chlorophyll and the presence of a stomachal cavity, &c. for the 

 digestion of crude food in the former, and the presence of chlorophyll and 

 absence of a stomachal cavity, as weU as of all means of taking in crude food 

 for digestion, in the latter, are distinguishing characters which at once place 

 Astasia limpida on the animal, and Euglena on the vegetable side, respectively, 

 of the great organic kingdom ; yet both Ehrenberg andDujardin have classed 

 Astasia and Euglena together." 



If the organic difference between Astasice and Euglence be what Mr. Carter 

 asserts, his proposition to divide the Astasiaea of Ehrenberg into two families, 

 viz. Astasiaea and Euglenaea, must be accepted. 



The Astasiaea inhabit ponds, mostly occurring on the sui^face, and frequently 

 tinge the water with their own colour when their multiplication has been 

 very rapid. WTien swimming, they present an elongated form, but when 

 fixed, often appear as round globules. From their beautiful colour, their 

 ever varying changes of form, and the rapidity of some of their \ital acts, 

 they are most interesting and pretty objects under the microscope, and from 

 their common occurrence are almost always at hand for the student. Many 

 are capable of progressing by alternately fixing and advancing the head and 

 tail after the manner of a leech, as well as by the usual process of swimming. 



Genus ASTASIA (XYIII. 36, 48, 49, 50).— Individuals free (not attached 

 by a pedicle), and fm^nished with a long or short tail, but no eye-specks. A. 

 pusilla is the only species in which vacuoles have been clearly seen. Ova 

 (granules) are perceptible in A. hwmatocles, and probably exist in the three 

 other species ; a locomotive organ in the form of a thread-hke proboscis exists 

 in A. pusilla. Perty unites this genus with Distigma. The immense num- 

 bers in which these Infusoria are sometimes developed in a few days, and the 

 blood-red coloiu" they impart, have not unfrequently been the cause of con- 

 siderable alarm and anxiety to persons residing in the vicinity of ponds or 

 small lakes which have become blood- coloured by their swarming. 



Dujardin's genus Astasia is defined as colourless, obtuse or rounded poste- 

 riorly ; whilst those described by Ehrenberg are mostly green or red, and 

 pro\^dcd with a longer or shorter caudal prolongation. 



