FF.ESHWATER LIFE INFUSOPJA. 291 



or conjugation may pften be observed; and I once met with a whole 

 colony, produced by progressive self-division, all thrusting out their 

 heads from the middle of a lump of jelly, which served as their common 

 envelope. 



The bell-shaped Vorticellce are famiHar to every microscopist, and 

 they are as beautiful as they are common. They are often so abundant 

 as to look like a white fluff clothing the roots and stems of aquatic plants. 

 The bell he.s no ciUa on its surface ; but from the open rim protrudes a 

 disk which bears a rotary wreath of these organs. In the depression 

 between rim and disk he the mouth and the excretory orifice close 

 together. The former opens into a well-defined gullet, which extends 

 some way into the interior, where also a contractile vesicle and a curved 

 nucleus may readily be discerned. Careful iUumination is needed to 

 show the contractile thread inside the tubular stalk. When a VorticeUa 

 breaks away from its place of attachment, as not unfrequently happens, 

 the bell may swim off with the stalk in tow. In one such instance I 

 observed the bell come to rest by its cilia on a bit of weed ; and while in 

 that position, the stalk every now and then contracted spiraUy as usual, 

 although the movement could be of no possible use to the creature. 

 This led me to think that the movement is ordinarily quite independent 

 of anything of the nature of will. Specimens may be met with in 

 various stages of fission ; and occasionally one or two small oval bodies 

 are found adhering to the stalk where it joins the bell, but what part 

 they play in the life-history of Yorticella I have not been able to witness. 



Continuous self-division increases the number of individuals by a 

 sort of geometrical progression. In such a way are pi'obably formed 

 those splendid compound clusters which, as in Carchesium poUjpitiam, 

 exhibit the magnificent spectacle of forty or fifty bells connected by their 

 ramifying threads with one common trunk. It is a fine sight to behold 

 a number of bunches all contract their fibi'es at the same moment to one 

 centre, the top of their common pedicel, and to si^read out again in loose 

 array as before ; and to see this done again and again, not by one 

 specimen alone, but by a colony of specimens crowding the bit of water- 

 plant under examination. I have taken Carchesium on AnacJuiris from 

 imder the ice in the month of January. 



Minute Vorticelhne forms are found in parasitic clusters on the 

 carapaces of Cyclops, Daphnia, and other Entomostraca ; on the sheUs 

 of water-snails, on water-beetles, and on various aquatic lai-vse. Not 

 that the so-called parasites actually feed upon the substance of their 

 host ; they do not claim board, but only lodging. They feed in the 

 surrounding element, as usual, by their ciha. Epistylis dirjitaUs infests 

 in thick masses the abdomen of Cyclops, having the appearance of an 

 elegant but rather cumbersome train. The bell-part is ^^j^ of an 

 inch long ; the little stalk is branched and non-contractile. A much 

 smaller species, with a simple stalk, has a length of no more than 

 5655 of 8,n inch. I have also met with a sessile form, fiUed with 

 grains of chlorophyll, and completely colouring the abdomen of the 

 unfortunate Cyclops green. Length of body from jlj to j-^'u of 

 an inch. 



