1880.] 



MICKOSCOPICAL JOUENAL. 



93 



Armed with two sucli lenses as I 

 have called attention to, the student 

 of histology is prepared to battle 

 with difficult questions of struc- 

 ture. I think I have learned by 

 experience in the use of the poor, 

 the medium, and a few of the best 

 lenses that the skilled opticians have 

 produced, what objectives afford 

 me the most accurate knowledge in 

 my studies. 



Bangor, Maine. 



The Simplest Forms of Life.* 



BY E. EYFEKTH. 



I. Order. Flagellata. (FlagelHfera.) 



Body not ciliated except at one 

 23oint in front, in some also behind, 

 provided with one or more very 

 long, moving, filamentous appen- 

 dages, — flagella, which, however, 

 are only made visible in many 

 forms by reagents ; at times they 

 are lost. In most forms contractile 

 vesicles are known ; a mouth is 



only distinguishable in certain 

 cases. All have a resting-stage, dur- 

 ing which they multiply by division, 

 and in their develojDment, as also in 

 their outward appearance, they are 

 closely related to the lower Algae ; 

 therefore they have, either in whole 

 or in part, been placed among the 

 latter by many authors. Among 

 recent investigators, v. Siebold, 

 Kolliker, Clauss and Ilackel, have 

 asserted their vegetable nature ; 

 Stein and Claperede have consid- 

 ered them as animals. Most of the 

 flagellata live as single, free swim- 

 ming individuals ; some are united 

 in families. 



The common assumption, that 

 the movement is produced by the ac- 

 tive flagella, has been contradicted 

 from many sides, for this cause 

 seems to be inadequate to produce 

 the result ; they may serve as rud- 

 ders. It is still uncertain what the 

 cause of the motion is. It can often 

 be seen that the animals can move 

 the flagella voluntarily, and with 

 considerable energy. 



Families. 



Flagella invisible. 



Surface of body rough, uneven, without membrane. 

 Surface of body hard, forming a membrane, 



living singly, without gelatinous coat (in motile stage), 

 membrane thin, body metabolic, 

 membrane thick or hard, body constant in shape, 

 living in families or single, 



with a common or special gelatinous covering, 

 without a covering, mulberry-shaped, 

 enclosed in a shrub-like, connective coat, 

 Flagella in one of the furrows which surround 



the hard carapace (often very distinct). 



Monadina. 



Astasisa. 

 Cryptomonadina. 



Volvocina. 



Hydromorina. 



Dinobryina. 



Peridinias. 



I. Family Monadina. 



Body without an external coat, but only slightly changeable, small, without any recog- 

 nizable organization. During observation the animal clings to the slide or cover, and 

 then seems to melt away, leaving minute glistening particles which were contained in 

 the body mass. A number of genera have been established by Ehrenberg, Dujardin, 

 Perty and others, which cannot be retained ; at least, they are not sufflciently studied. 

 The following deserve a place here, but some of them should belong to the cryptomo- 

 nadina (Chilo7no7ias, Heteroniita). 



* Translated from the German, by the Editor. 



