1893.1 MICIlOSCOl'K'Al. JoT/nXAL. 185 



extcriKil water, yet it can \>v done, juul it lias hecn done. In- 

 d<M(l, I liavc iic'r.><()nally had the satisfaction ofdoinj: it. 



Students of this chiss of microscopic animals helieve that the 

 endnplasm is everywhere" pierced hy exceedinf,dy minute canals 

 which lead to the contractile vesicle, and pour into it whatever 

 they may have received. These more than microscopic chan- 

 nels cannot he seen, but that ?omethin^^ corresjtondinji at least 

 in function to such canals, exists within the infusorial endo- 

 plasm, there can he no douht. And if. even in tlie lar^rtst In- 

 fusoria, they are too minute to he seen with the hest of modern 

 objectives yet do not fail in their function of carrying; liquid to 

 the contractile vacuole, their iiivisihility is no argument against 

 the existence of minute ])ores in the extremities of the surface 

 villi on the contractile vesicles of the naked Hhizopods referred 

 to. It is not making an unreasonable use of the imagination 

 to say, that the conduct of the contractile vesicles of Paramae- 

 civin avirlid suggests exactly that interpretation. These vesi- 

 cles are normally sub-spherical; it is usually only when the an- 

 imal is in distress, or is pressed U])on too heavily l>y the cover- 

 glass, that they assume the stellate form with the 1 "ranches ra- 

 diating from a central vacuole outwardly into th- endojilasm. 

 Is it not reasonable to sn]'))ose that the contents should then be 

 backed up into these ordinarily invisible channels to distc-.id 

 them r.nd to make tln'Ui cons])icuous ? It is absolutely be- 

 yond a doubt that the Infusoria and other microscojiic iinimals 

 have no more contiol over the pulsations of their contractile 

 vesicles than the human l)eing has over the movements of his 

 own heart. If the contrary was the case, there need not be any 

 undue enlargi nient of the vesicle, or any backing up of the vac- 

 uolar contents in these conditions of uncomfortable pressure, 

 or of uncongenial surroundings. 



No atjuatic microscopic animal can swallow a particU' of food 

 without at the same time swallowing a greater bulk of water. 

 It is an every-day oc urrence to see an Infusorian engulf a 

 smaller, living animal, which is accomi)anied into the endo- 

 plasm by u comparatively huge drop of water. And it is a 

 common occurrence to see that animal live and move and strug- 

 gle until the water-drop has been absorbed so as to allow the 

 food-mass to come in actual contact with the digestive i)roto- 

 plasm. What becomes of that water ? Infusoria are voraci- 



