liKPRESEXTATn HS O/-' l.V/U.l/. I'IIYI.\ (>.') 



one near ci) licr cud »»f t lie aiiiiiial as circular clear spots int«» w hi(;li 

 from seven to ten slarlikc radiations convey li(|iiids from oiitlyinn 

 regions of the protoplasm. These rndiatiiKj ciukiIs may be seen 

 at the times the vacuoles contract and are hesf seen in prepara- 

 tions which are beginning to dry. 



The central mass of protoplasm in the animal, tin; endoplasm. 

 appears devoid of particular structures when examined without 

 special treatment. It is much more fluid than the ectoplasm and 

 appears granular. It generally contains a number of fond 

 vacuoles, with food in various stages of digestion. The two 

 nuclei, a large macronucleus and a small micromicleus, are 

 embedded therein. It is usually very difficult to make out either 

 in normal animals. Study a stained slide for an idea of these 

 structures. The macronucleus is a large lobed mass near the 

 center, and the micronucleus is a small spherical body lying in a 

 concavity of the macronucleus. The micronucleus plays an 

 important role in reproduction. 



The food of this animal is mainly bacteria, decaN'ing organic 

 matter, and minute protozoa. The mouth is located at the 

 base of the oral groove and opens into a funnel-like, S-shaped 

 pharynx or guUet which leads oblic]Ucly toward the hindermost 

 end into the endoplasm. The arrangement of cilia about the 

 oral groove is such that a steady current bearing food particles 

 is directed toward the mouth. If possible, observe an animal 

 feeding. Food particles are wafted down the pharynx by its 

 ciha which are fused into a so-called undulating membrane. The 

 particles collect into gastric vacuoles at the end of the pharynx. 

 These food vacuoles are then carried through the protoplasm in a 

 more or less definite course during the process of digestion and 

 absorption and the undigested portion is voided through a small 

 permanent anal spot in the surface of the body just behind the 

 pharynx. The firm cuticle, giving definiteness of form, has 

 necessitated the presence of oral groove, moutli. pharynx, and 

 anal spot as permanent organs. 



Reproduction takes place by transverse division (binary fission) 

 of the animal into two daughter individuals. A.ssoeiated with 

 binary fission are the phenomena of conjugation iluring which 

 the oral surfaces of two animals are connected by a protoplasmic 

 bridge. Across this bridge there is an exchange of micronuclear 

 material. Illustrations of fissicm and conjugation may be ft>und 

 in the culture, but, if not, demonstration mounts of stained 



