428 ORDER FLAGELLATA-EUSTOMATA. 



slender throughout, and equal to from one and a half to twice the length of the 

 body in their completely extended state, which they usually assumed under the 

 influence of this reagent. Aided by the experience of a post mortem examination, 

 it was not so difficult to recognize their character and relative position in the living 

 examples. In the more easily examined stationary condition one of these flagella, 

 which may be termed the superior one, is thrown backwards in an arcuate fashion 

 over the dorsal border. The second or inferior flagellum meanwhile remains coiled 

 in a spiral form close against the entrance to the oral aperture, and with its distal 

 extremity only protruding and attached to the surface of the slide or cover-glass. 

 Vibratory action, serving the purpose of entrapping food, belongs apparently, chiefly 

 if not exclusively, to the first-named appendage, which usually during the sedentary 

 condition exhibits rapid vibratile movements throughout its distal region. These 

 vibratory motions, combined with the convolute disposition assumed by both flagella, 

 frequently impart to the animalcule an appearance of possessing several shorter 

 filaments, and thus invalidate the interpretation originally connected with the 

 number of these appendages as given by Dujardin. When swimming actively from 

 one spot to another, or rushing about as it is accustomed to do when disturbed, the 

 animalcule is driven backwards through the water by means of the flagellum 

 that remains comparatively inactive and affixed to the ground during the stationary 

 condition, but which is now stretched out anteriorly to its full extent and 

 vigorously lashed from side to side, causing the body to rotate upon its axis alter- 

 nately from right to left and left to right as motion in a backward direction is 

 effected. The primary or vibratile flagellum during natation appears to be coiled still 

 more closely and completely within the pre-oral excavation. Particles of carmine 

 were eagerly incepted by the specimens under examination, their favourite food being 

 however the various smaller monads and algae spores contained abundantly in the 

 same infusion, and which were brought within reach during the sedentary condition 

 of the animalcule by the rapid vibratory motions of the primary flagellum. These, 

 though nearly equal in diameter to their own bodies, were swallowed whole, the 

 loop-like convolutions of the basal portion of the inferior flagellum apparently 

 aiding in pushing these food-substances into the oral cavity. Various vacuolar 

 spaces and more solid spherical bodies were frequently observed within the other- 

 wise clear endoplastic substance, one of the former towards the anterior extremity 

 and immediately above the oral excavation representing apparently the contractile 

 vesicle, its pulsatory properties not however being very vigorously manifested. 

 During life, and for a considerable time after death by a natural process, the external 

 cuticle of this animalcule appears to possess a considerable amount of rigidity, being 

 often found, indeed, in the latter case as a mere shell devoid of all trace of the 

 endoplasm and flagellate appendages, and exhibiting under such conditions, as 

 shown at PL XXIV. Figs. 58 and 59, a sharp and clear outline of its peculiar unsym- 

 metrically angular form. Under the treatment of dilute osmic acid the entire body 

 however rapidly disintegrates, first assuming a rounded or spherical outline and then, 

 as it were, melting gradually away. Increase by transverse fission, Fig. 57, is the 

 only form of reproduction as yet positively ascertained to occur. 



As already intimated, the Glyphidium marinum of Fresenius is beyond doubt 

 identical with the present species. The examples referred to this type, figured 

 by Cohn, also entirely harmonize with the form here introduced, excepting that the 

 body is slightly shorter in proportion to the width and more evenly rounded pos- 

 teriorly. The character of the flagella, while more accurately appreciated by 

 Fresenius, is not fully elicited by either of these authorities ; in some instances two 

 flagella are figured, but in others a single one only is represented. The oral aperture 

 is further described and figured by Cohn (see PL XXIV. Fig. 29) as apparently 

 supplemented by a projecting, undulating, lip-like membrane, such structure being 

 here readily identified with the optical aspect only of the loop-like convolution of the 

 inferior flagellum. 



