GENUS HETEROMITA. 293 



the scene. Additional details respecting the discovery of this s])ecics both in its adult 

 and sporular conditions, in intimate connection with both hay and growing grass, are 

 recorded at page 136 ct scq., of Chapter IV. (see also iipiter jjortion of PI. XI.) 

 devoted to the subject of Spont;ineoiis (Jeneration. 



So remarkal)le a likeness subsists between the so-called billagellate " zoospores " 

 of the potato-fungus, Penmospora ivfcstans, figured by Mr, Worthington Smith in the 

 'Monthly Microscopical Journal' for September 1876, and the typical adult zooids 

 oi Jldroviita lens as here figured and described, that the author is unable to repress 

 a suspicion that these presumed zoospores actually represent examples of the j^resent 

 cosmopolitan animalcule. Not only are the sizes of the bodies and the various 

 shapes assumed absolutely identical, but even the presence of an endoplast and 

 contractile vesicle, which occupy precisely similar relative positions, is clearly though 

 unconsciously indicated in Mr. Smith's drawings. The abundant and almost 

 invariable development of //. lens in connection with decaying foliage and other 

 vegetable matters derived from well nigh every source, renders it not only jjossiblc but 

 highly i^robable that the spores of these aniinalc;ules were imported with the potato 

 leaves that formed the subject of Mr. Worthington Smith's investigation, freely 

 developing side by side with the germs of the cryptogamic plant, and during their 

 quiescent states so closely resembling them that their distinct nature and independent 

 origin escaped detection. 



Heteromita rostrata, S. K. Pl. XV. Figs. 18-28. 



Body clongatc-ovatc, somewhat inflated posteriorly, the anterior ex- 

 tremity pointed and usually slightly recurved towards the ventral aspect ; 

 flagella equally slender, the anterior vibratilc flagcllum from one and a half 

 to twice the length of the body, the posterior one, or gubcrnaculum, longer 

 than the preceding, contracting, when the animalcule is attached, in a 

 loose spiral coil ; contractile vesicle mostly conspicuous, situated close to 

 the anterior extremity ; endoplast located near the opposite or [)ostcrior 

 extremity. Length of body 1-3000". 



Hab. — Putrefying fish macerations. 



The above title is here conferrerl upon the species figured and described by 

 Messrs. Dallinger and Drysdale * under the name of the " Springing Monad " the 

 springing action suggesting the name being caused by the rapid coiling anrl un- 

 coiling of the longer anchoring or gubernaculate flagellum in its fixed condition. 

 A similar leaping motion through the contraction of the gubcrnaculum being 

 common to various other species of the genus Heteromita, the technical name here 

 adojjted has been conferred upon it more particularly with relation to the peculiar 

 beak-like or rostrate contour of the anterior extremity of the body. The develop- 

 mental and rejjroductive phenomena of this form as carefully foUowefl out by its 

 discoverers, corresjjond broadly with those of the many other monadiform animal- 

 cules they examined. Multiplication by the ordinary process of longitudinal fission 

 represents the commonest and most conspicuous mode of increase, the two flagella 

 as shown at PI. XV. Fig. 19, participating in the du];licative process. Certain 

 animalcules, however, assume a spherical quiescent state and split obliquely or 

 transversely into halves, each such divided portion swimming away in a form not 

 distinguishable from the typical zooids. Further tracing these motile units, it was 

 found that they did not attach themselves by their anchoring flagella, but wandered 

 about until they came in contact with the ordinary sedentary monads, and with which 

 they immediately coalesced. The ultimate result of this genetic fusion was the 

 production of triangular encystments, which sub.sequently dehiscing at their three 



* ' Monthly Microscopical Journal,' Dec. 1873. 



