THE SIMPLER ORGANISMS 75 



oblong meganucleus and a little round micronucleus close 

 beside it. The former at least should be visible in the live 

 animal. 



10. Mount another drop of clear water containing 

 paramoecia, first adding to it a little finely powdered car- 

 mine, stirring the carmine through the drop. Cover, remove 

 excess of water, find a little group of paramoecia in some 

 more or less restricted area, among trash, or at the edge of 

 the cover, and watch them eat the carmine. It is wholly 

 indigestible and may be followed in its entire course through 

 their bodies. Unless the mounting, stirring, covering and 

 finding be done with unusual celerity, bright red food-balls 

 of carmine will already be seen within the protoplasm of 

 the animals when first looked at. Other food-balls may be 

 seen forming in the neck of the funnel-shaped rudimentary 

 esophagus that leads inward from the mouth, and those first 

 formed may be seen in their course of circulation round the 

 body, and may in a little while be followed through their 

 entire circuit. 



11. Mount another drop containing paramoecia, adding 

 thereto a little methyl green or iodine. Cover and study 

 carefully the details of cellular structure : 



a) Ectosarc and endosarc. 



b) The peristome and its fringing cilia, and the 

 esophagus. 



c) The cilia of the body in general and of the posterior 

 end in particular. 



d) The stinging threads which the reagent used caused 

 to be thrown out from the ectosarc. These will be 

 seen among the cilia along the sides of the body, and 

 will be distinguishable therefrom by their irregularity 

 and unevenness of length, and by their different 

 mode of attachment to the ectosarc. 



e) Meganucleus and micronucleus. 



f) Vacuoles and food-balls. 



