J""*'! Skarle, The Pond and its Inhabitants. 27. 



1917 J ' J 



their shock, and one l)y one emerge their beautiful plumed 

 crests. Selecting an individual best placed for observation, 

 we notice that the crown of plume-like tentacles is attached 

 to a horseshoe -shaped disc called the lophophore (meaning 

 "crest-bearer"). Each tentacle is fringed on both sides with 

 hair-like processes called cilia, which are kept in constant 

 vibration. The motion of the cilia is all in one direction, so 

 that their combined action produces a vortex, bringing fresh 

 streams of water for respiration, and drawing particles of food 

 down to the mouth, situated between the arms of the lopho- 

 phore. Over the mouth is placed a finger-like process, wliich 

 may help in the selection of food or in the rejection of objection- 

 able matter that might be whirled into the vortex. This organ 

 is called the epistome (Gr., " upon the mouth "). The mouth 

 opens into the alimentary tube, consisting of oesophagus, 

 stomach, and intestine, and is bent back upon itself so that 

 the vent opens at the back of the tentacles near the mouth. 

 As the food particles pass in through the mouth we can observe 

 the process by which nutrient parts are absorbed and the 

 refuse matter ejected. Their food consists of diatoms, desmids, 

 protozoa, rotifers, &c. When the food particle reaches the 

 stomach it is tossed up and down by muscular contractions 

 and dilations of the stomach until the digestible portion has 

 l)een absorbed, when the waste material is packed into the 

 intestine. When this waste matter has to be discharged the 

 orifice of the intestine is protruded, and when the operation 

 is over it is withdrawn again. 



Plumatella is a very timid creature, and the slightest shock, 

 such as the jarring of the table, causes it to withdraw its 

 tentacles. This action is effected by long muscles, which, by 

 contraction, pull the animal into its cell : similar contractions 

 of the muscular neck of the cell, which is attached to the 

 animal just below the lophophore, is the means by which the 

 tentacles are protruded. Attached to the part of the stomach 

 where the intestine bends round is a long twisted organ called 

 the funiculus (" a little rope "), which goes to the bottom of 

 the cell. Attached to the funiculus is the testis, or male 

 generative organ, while in the internal tube, attached to a 

 short peduncle, or footstalk, the ovary is })laced. In these 

 ovaries true eggs arc developed, from which are hatched ciliated 

 larva. These swim about rapidly for a time, and then attach 

 themselves to some flat surface and develoj) and bud into two 

 polypides, which soon grow into a new colony. But they 

 have another and highly interesting mode of reproduction ; 

 this is by means of asexual resting l)odies, called statoblasts, 

 or stationary germs. These are produced from the funiculus, 

 and are never hatched in the colony when they are produced. 



