764 



MICROSCOPIC FORMS OF ANIMAL LIFE 



Professor James -Clark (U.S.A.), 1 followed by those of Stein, Saville 

 Kent, 2 and Bergh. In some of these a sort of collar-like extension of 

 what appears t<> be the protoplasmic ectosarc proceeds from the anterior 



extremity of the body (fig. 585. d). forming a kind of funnel, from the 

 bottom of which the flagellum arises ; and by its vibrations a cur- 

 rent is produced within the funnel, which brings down food-particles 

 to the 'oral disc ' that surrounds its origin while the ectosarc seems 

 softer than that which envelops the rest of the body. Towards the 

 base of the collar a nucleus (?/) is seen; while near the posterior 

 termination of the body is a single or double contractile vesicle (cr). 

 The body is attached by a pedicel proceeding from its posterior 

 extremity, which also seems to lie a prolongation of the ectosarc. 

 These animalcules multiply by longitudinal fission : and this, in 

 some cases (as in the genus M<niiixi<j<i}, proceeds to the extent of a 

 complete separation of the two bodies, which henceforth, as in the 



irdinary Monadina, 

 live quite independ- 

 ently of each other. 

 But in other forms, as 

 Codosiga, the fission 

 does not extend througl i 

 the pedicel, and the 

 twin bodies being thus 

 held together at their 

 bases, and themsehv- 

 undergoing duplicative 

 fission, clusters are pro- 

 duced which spring 

 from common pedicels 

 (fig. 5H6) : and by 

 the extension of the 

 division down the 

 pedicels themselves, 

 composite arborescent 

 fabrics, like those of 

 zoophytes, are pro- 

 duced. 



In another group a structureless and very transparent horny 

 calyx, closely resembling in miiiiatiire the polype-cell of a Gampanu- 

 Ifiria, forms itself round the body of the monad, which can retract 

 itself into the bottom of it; and in the genus Salpingceca both 

 calyx and collar are present. In some forms of this group imilti- 

 plication seems to take place, not by fission, but by gemmation; 

 .-Hid, as among hvdroid polypes, the i/i'iitnni'- may either detach 

 themselves and live independently, or may remain in connection 

 with their parent stocks, forming composite fabrics, in some of which 

 the calyces follow one another in linear series, while in others they 



cr 



FIG. 585. Single zo 

 collar ; ti. nucleus ; 



iid 

 cv, 



>t' Codosiga innbellata : rl, 

 double contractile vesicle. 



1 Sec bis memoirs in Ann. \'nl. I/ixf. si-r. '', vol. xviii. 18(50; op. cit, ser. 4, vol. i. 

 18G8 ; vol. vii. 1S71 ; and vol. ix. 1s7'2. 



- Sec his Mninni! ,,/ fl/r Infusoria, issn-su, 2 vols. and 1 vol. of plates. 



