230 S. O. MAST 



at the base by a band of large powerful cilia. The rest of the 

 surface of the creature is sparsely covered with cilia which are 

 relatively long but very delicate. The knob-like protuberance 

 containing the mouth, and the adjoining tissue containing the 

 band of oral cilia will be referred to as the head, and the tissue 

 immediately back of it as the neck. Fig. i. 



HABITS 



Specimens of Lacrymaria are relatively scarce in nature. 

 They are occasionally found in cultures containing decaying 

 aquatic plants but never in great numbers. One rarely finds 

 more than two or three in a drop of solution. They usually 

 appear in the debris which collects at the surface of the water, 

 and under the microscope are found well concealed among 

 fibrous algae and masses of various other substances which con- 

 stitute the debris. Hidden away thus they frequently remain 

 in a given place for many minutes practically motionless with 

 the exception of the anterior end, the end containing the head 

 and neck. This end stretches out, often to a surprising distance 

 and turns in all directions, ujjward and downward, to the right 

 and left, darting rapidly backward and forward, apparently 

 exploring every nook and crevice within its reach, back of it 

 as well as in front, with the most astonishing agility and free- 

 dom of motion. Not only is this neck-like proboscis turned 

 in various directions as a whole but it may curve in an endless 

 variety of ways. Thus it is frequently seen to double back on 

 itself and to bend around objects in such a way as to form sharp 

 angles as represented in Figs. 4, 6 and 7. 



In these exploring reactions which have to do with the pro- 

 curing of food, I have often seen the neck stretchout, becoming 

 gradually thinner and thinner until it extended to a distance 

 equal to eight times the length of the body and was but little 

 larger in diameter than one of the oral cilia. We often marvel 

 at the length of the neck of the giraffe and the freedom of move- 

 ment of its head and are baffled in attempting to explain how 

 in the process of evolution it came to be what it is. And yet 

 the neck of this animal is scarcely as long as its body. If it 

 were relatively as extensible as that of Lacrymaria we would 

 find the giraffe browsing leaves from the tops of trees well 

 toward one hundred feet in height, and if it were relatively 



