322 FRESHWATER LIFE INFUSORIA. 



the transparent envelope, two contractile spaces, a nucleus and nucleolus, 

 short gullet, mouth, depression on the ventral side leading thereto, and 

 chlorophyll granules diffused through the fluid contents of the interior. 

 Transverse fission has been observed, when the nucleus separates into 

 two, each half being accompanied by its nucleolus. At the same time 

 contractile cavities form themselves in each segment into which the 

 body divides. I have observed frequent instances of true conjugation of 

 Paramecia, twice in the month of January. They pair by placing 

 themselves side by side. But I have occasionally seen two individuals 

 swim about for a long time grappled end to end, and then come apart without 

 actual conjugation. The cilia were unusually active at the point of 

 junction. In Paramecium aurelia two contractile vacuoles are seen, each 

 branching out star-fashion into short canals, which appear distinct 

 during the contraction of the central cavity, and are almost obliterated 

 during dilatation. I have found this pretty species swarming in stagnant 

 pools in spring. 



Kerona, or Stylonijchia, may be recognised by its slipper-like form, 

 and the long spines and bristles wdth which it is furnished at both ends. 

 In length it ranges from l-27oth to 1-lOOth of an inch. The body is also beset 

 with smaller setae, besides the active cilia by which it moves. A line of 

 these organs leads to the mouth, which is fringed with them. The mouth 

 itself is placed a little to one side, and is clearly indicated by the streams 

 of floating particles which set towards the spot. In the rear of this 

 opening is situated a contractile space, which dilates slowly but contracts 

 suddenly, the whole movement taking about six seconds to complete. 

 These animalcules have the queer habit of jerking hack at short intervals, 

 as they make their way through the water. Sometimes two individuals 

 will fasten on to each other by their terminal spines, and swim about 

 so connected for a considerable time. The two species answering to the 

 above description are A'. viytUus and K. siJurus. Another common 

 species, A', polijporum, is beau-shaped, filled with numerous vacuoles, and 

 armed with several hooks, but not with the long spines or bristles of the 

 preceding. It is parasitic on other freshwater animals. 



Euplotes charon belongs to a family of Infusoria which are charac- 

 terised by the possession of a lorica. The body, in fact, is encased above 

 in a boat-shaped horny shield, ornamented with lines of prominent dots. 

 The organs of locomotion are very highly developed. Cilia, bristles, and 

 hooks make the little creature quite foiinidable, and enable it to swim, 

 crawl or climb, back upwards or downwards, with the greatest agility. 

 A contractile vesicle and a nucleus are present. Euplotes may be looked 

 for amongst Alga) and other water-plants at all seasons. 



Amphileptuii resembles, both in form and movements, a small leech, 

 having a highly extensible proboscis, or prolonged upper lip. The other 

 extremity tapers to a tail. Hows of cilia are disposed lengthwise over 

 the entire body ; but these organs, as usual, are most conspicuous about 

 the mouth. The interior is diversified by numerous food-vacuoles. One 

 species, taken last June, seemed to me to be undergoing transverse self- 

 division. I have generally found it amongst duck- weed. 



