82 



rilK AMKUUAN MoNTIlI^V 



Maivli, 



II. Rkst rKiiioi) ok \'i:sui.i: : A\ki{Ac;k Ti.mi;. J^ Sixonh. 



Movements. -VorluitV hejjins to contract. 

 Position. — N'orluilV in same position. 

 Canals in same position. 



III. HlASTOLK OF VeSICI.E : AvKKAOM TlMK. >,i) Sk<0\I»S. 



Movements. — Vesicle expands sudilcniy at first, then slo\vl\ . 



V^orlKife contracts at first ami tlieii slowlv «.'\paiuls. 

 Position. — V'esicle exjiamls from a central j>oint. 



VorlnUV in same position. 



Canals in same position. 



Enough has been said concerniiiL^ tiie Ljoncral stnicturf (»!' the 

 contractile vesicle ; let us now turn our attention to its probable 

 function. In the tirst place, it should be determined whether 

 the content of the vesicle is a ijas or a litpiid. I am (|uite fiillv 



ExiM.ANA TION OF 1 IIK I-'l(ilHK. 



/*(/ ra)incium an rcl in . 

 c. v., contractile vesicle in diastole, n. s.. vesicular systole. 

 Vii., Vorhofe. c canals, n., nucleus, o.. n-sophagus. es., 

 ectosarc. en. s.. endosarc. f. b., food vacuoles. f\ b., food 

 bolus in process of formation. 



convinced that it is a gas. because microscopicallv it gives the 

 appearance of a gas bubble suspended in a lifpiid or a semi-lif)iiid. 

 I liave tried various stains and in no case was the contents of the 

 vesicle stained, either before or after the death of the Paranie- 

 riu/n. If there were a liquid it would certainly be stained after 

 the death of the animal if not tluring life. I have also often 

 noticed that when the organism slowlv died the vesicle enlarged 

 to such an extent as to rupture the cell-wall and allow the con- 

 tents of the vesicle to protrude as a gas bubble which was finally 

 absorbed Iw the water. The composition ofthisgasis not known. 

 It is probably a gas formed by metabolic processes going on in the 

 living fjiganism. 



