244 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The organisms placed in this division are characterized by the fact that 

 the motile stage forms the chief period of their lives ; and this stage 

 is not only that which is relatively the longest, but that also in which 

 the organism best exhibits its nutrient and growing activity. The 

 objection that it is often impossible to separate the Mastigophora from 

 certain of the simpler Sarcodina, as well as from certain simpler 

 vegetable organisms, such as the Protococcoid Algse, the Myxomycetes, 

 and the Chytridese is to be met by the reflection that all these forms 

 have a common origin. 



The Mastigophora may be divided into four subdivisions or 

 orders : (1) Flagellata, or forms which have flagella without either 

 superadded cilia or " collars " ; this is the largest and most varied 

 group. (2) Choano-flagellata have a collar at the base of the single 

 flagellum, which calls to mind the collared or so-called endodermal 

 cells of sponges. (3) Cystoflagellata have a retiform structure of 

 their protoplasm, not unlike that which is seen in plants ; and they 

 are, further, characterized by their peculiar form, and, possibly also, 

 by their reproductive phenomena. The (4) Cilio-flagellata have cilia 

 as well as flagella. 



An interesting historical review is followed by the citation of 

 206 separate works or essays. The Flagellata are divided into the 

 (1) Monadina, which are of simple structure and have one flagellum, 

 or two small ones ; there is no special oral orifice, or it is simple and 

 is not continued into a well-developed pharynx. (2) Euglenoidina : 

 these are better developed forms of some considerable size, ordinarily 

 provided with one, but in some cases with a second small or large 

 flagellum. The so-called mouth at the base of the flagellum is con- 

 stantly present, and often leads into a distinct pharynx. (3) Iso- 

 mastigopoda, with two or, more rarely, four or five subequal flagella ; 

 mouth rarely developed, and nutrition very ordinarily elfected as in 

 plants. (4) The Heteromastigopoda have two flagella at the anterior 

 end, which are equal or unequal in size, and are respectively directed 

 forwards and backwards. 



The structural and developmental characteristics are entered on, 

 and treated of in detail, but the arrangement of the genera and species 

 is not yet begun. 



New Infusoria. — D. S. Kellicott describes * a Cothurnia, a 

 parasite of the .crayfish in America, to which he gives the specific 

 name of variabilis, as he finds it to vary so much. The lorica is 

 about twice longer than broad. Seen from the side, it is strongly 

 ventricose, and uniformly convex posteriorly. The neck is narrow, 

 its width being less than half that of the carapace; the laterally 

 compressed orifice is set very obliquely, sometimes quite vertically, 

 with the upper edge produced into a cusp, and with a tooth-like angle 

 in the middle of either margin; the aperture is sometimes awry, 

 turning the cusp to one side of the axis of the shell. The peduncle 

 is short, not exceeding, as a rule, one-fourth the length of the lorica ; 



* Bull. Buffalo Naturalists' Field Club, i. (1883) pp. 112-4 (5 figs.). Proc. 

 Amer. Soc. Micr., 6th Ann. Meeting, 1883, pp. 105-7 (5 figs.). 



