296 Ai^count of pKofe^sor: JO^r^nberg's 



young animals ; the body of the parent consists of a transparent 

 sac or capsule, in which several young ones are inclosed, and 

 each of these is provided with a single red eye and a long bristle, 

 which it exserts through the transparent envelope (Fig. 12.) 



In further prosecuting his researches on the eyes of the Poly- 

 gastric Infusoria, Dr Ehrenberg, who had naturally expected to 

 meet with these organs chiefly among the larger kinds of infu- 

 soria, found to his surprise that they are a far more general at- 

 tribute of the smallest sort. For instance, in the family of the 

 Monads, he discovered two genera with evident eyes. One of 

 these, Microglena, consists of two species, the smallest individuals 

 of which do not exceied j J ^ of a line in diameter (Fig. 13 and 14.) 

 The other belongs to the Loricated Monads. Its body is bright 

 green, contained in a transparent shell, and furnished with a 

 large bright red eye. He has named this genus Lagenula, from 

 its shell, which is shaped like a bottle (Fig. 15)*. The pre- 

 sence of eyes, both in the naked monads, and those provided 

 with a shell, serves as an additional proof of the correctness of 

 the view which induced Dr Ehrenberg to arrange the infusoria 

 in two parallel series, the Niida and Loricata, the latter of which 

 differ from the former chiefly, and in many cases solely, in pos- 

 sessing a shell. 



III. Of the External Parts of the Body, and External Organs of 

 the Infusoria. 



In order to obtain appropriate characters for the systematic 

 arrangement of the numerous forms of infusoria, which, chiefly 

 through his own researches, are now known to exist, Dr Ehren- 

 berg has found it necessary to examine, with greater care than 

 has hitherto been done, the external parts of these animals, and 

 to define them with greater accuracy. I shall endeavour to give 

 some connected account of the more interesting results of his in- 

 vestigation, without entering into details, which rather belong to 

 the terminology of the subject, and possess no general interest. 



• By means of an improvement in his microscope, he has lately disco- 

 vered two additional loricated monads with eyes, which he names Cryptogkna 

 pigra, and Cryptoglena agilis, the former ^'^ of a line in diameter, the latter 

 not exceeding 5^5 of a line, being little more than half the diameter of a glo- 

 bule of human blood. 



