FEEDING HABITS OF FRESHWATER MUSSELS. 13! 



It is extremely difficult to observe the cilia which lie at the 

 bottoms of the furrows (mf). Wallengren (I.e.) ascribes to them 

 the duty of carrying lengthwise of the furrow to the lower margin 

 of the palps the minute particles that may fall between the ridges. 

 But Siebert ('13) thinks they lead in the opposite direction. 



In the event that any particles get past the palps they may still 

 be rejected at the mouth. A strong compression of the lips will 

 force them outward to the edge of the lips, where they encounter 

 the cilia directed backward (Figs. 3 and 4, lower margin) and are 

 carried to the edge of the palps and dropped into the mantle 

 chamber. 



The outer surfaces of the palps and lips have as their function 

 the removal of particles from the mantle chamber (Fig. 4). 



McAlpine's (I.e.) observations upon the movements of detached 

 parts led him to conclude that the palps and gills have nothing 

 to do with feeding, and that they are concerned only with carry- 

 ing away foreign material. But Wallengren's (I.e.) conclusions 

 are based upon far more careful and logical experiments, and 

 Siebert's (I.e.) recent paper on the epithelium of Anodonta is of a 



confirmatory nature. 



OBSERVATIONS. 



The ciliary currents may be observed quite readily on a mussel 

 from which the shell and mantle of one side have been removed, or 

 on detached parts, which, as stated, continue to exhibit ciliary 

 activity for a long time. Small quantities of carmine, indigo, or 

 other nearly neutral coloring matter may be dropped upon the 

 part to be studied, and their behavior noted. Care must be 

 exercised in the amount of water used. The less water the 

 better, within limits, for in a large amount of water currents 

 may obscure the action of the cilia. The surface of the organ must 

 be level in order to offset gravitational disturbance. A small 

 piece of any ciliated organ, when placed in a watch glass with 

 water and a very little color, will show under low power both the 

 cilia and their currents in great detail. 



The Ciliary Streams. 



The figures will show more clearly than description the course 

 of the streams of material collected from the water. All the 



