390 



SCIENCE 



[N. S. Vol. XXXin. No. 845 



3. Dogfish recognize and determine the location 

 of food substances through a chemical sense. 



4. This power is lost when the olfactory cap- 

 sules are filled with loose cotton. It is regained 

 when the cotton is removed. 



5. The plugging of one nostril only does not 

 seriously ailect this power. 



6. The dogfish obtains its food almost, if not 

 entirely, through the use of the sense of smell. 



7. The selachians possess a true sense of smell, 

 comparable to that of the terrestrial vertebrates. 



The complete paper will appear in the Journal 

 of Experimental Zoology. 



Eabits and Reactions of the Ciliate, Lacrymaria: 



S. 0. Mast, Goucher College. 



Laorymaria is usually found with the body well 

 concealed in dgbris while the head stretches out 

 in all directions and moves rapidly about forward 

 and backward and from side to side apparently 

 exploring every nook and crevice within its reach 

 which often extends to a distance equal to eight 

 times the length of the body. In this way the 

 creature captures other organisms on which it 

 feeds. It never swallows dead particles, showing 

 that it exercises the power of selection in the 

 process of feeding. 



It is usually assumed that the movements are 

 regulated by the contraction of tissue in the neck 

 and body, but this is not true. The head is not 

 thrust out; it is pulled out. Nearly all of its 

 actions are due to the activity of a band of power- 

 ful cilia which extends around the mouth. Thus 

 Lacrymaria is much like an organism composed 

 of two independent parts united by means of an 

 extremely elastic substance far more elastic than 

 any known lifeless material. When the neck is 

 fully extended it is frequently fifty times as long 

 as when contracted. 



There is no indication of orientation in Lacry- 

 maria under any condition. It does not respond 

 to light. None of its reactions fulfil the demands 

 of any of Loeb's definitions of tropisms. The 

 movement of the entire organism is almost en- 

 tirely regulated by the reactions of the head, and 

 the direction of movement of the head is regu- 

 lated almost entirely by internal factors; it is 

 practically independent of the location of the 

 stimulus. We assume that all of the reactions 

 in this animal are definitely determined by 

 physico-chemical processes, but whether they are 

 or not has by no means been demonstrated. 



The complete paper will probably be published 

 in the Journal of Animal Behavior. 



The Reaction System of the Flagellate, Peranema: 



S. 0. Mast, Goucher College. 



Under natural conditions Peranema rarely 

 swims. It ordinarily moves in contact with the 

 substratum without rotating. Only the tip of the 

 flagellum is active. This is bent at right angles 

 to the rest and strikes strongly backward. When 

 the organism is stimulated no matter by what 

 means or at what point it responds by turning 

 the anterior end with the flagellum sharply, al- 

 ways toward the same side. Then it straightens 

 out and proceeds on a new course usually at an 

 angle of about 90° with the old. If the stimulus 

 does not cease the same reaction is repeated until 

 it does. This is the only method which Peranema 

 has for changing its course in its usual method 

 of locomotion. The action of the flagellum is not 

 functional in this. If strongly and repeatedly 

 stimulated a larger portion of the flagellum may 

 be brought into action and there may be peris- 

 taltic contractions in the body. Both of these 

 processes afi'eet the rate of motion but not the 

 direction. The direction of turning is entirely 

 dependent upon internal factors; it is independent 

 of the location of the stimulus on the body. The 

 direction of movement is not definitely determined 

 by external factors. It is dependent upon " trial " 

 positions which are assumed by turning the an- 

 terior end in response to a stimulus; only such 

 as do away with the action of the stimulus are 

 followed up. 



The complete paper will probably be published 

 in the Journal of Animal Behavior, 



The Behavior of Certain Arthropods m Relation 

 to Color Environment: A. S. Peaese, Univer- 

 sity of Michigan. 



As a" result of experiments with crayfishes, 

 caddis-fly larvae, spider-crabs and spiders the con- 

 clusion is drawn that protectively colored arthro- 

 pods do not select an environment similar to their 

 own; at least they do not make such selection on 

 account of color. 



The complete paper will be published in the 

 Journal of Animal Behavior, Vol. I., pp. 79-110. 



On the Regenerative Power of the Dissociated 

 Cells in Bydroids: H. V. Wilson, University 

 of North Carolina. 



It had been shown that when certain sponges 

 are broken up into their constituent cells, the 

 cells will reimite and form masses capable of 

 differentiation into functional sponges. Two 

 hydroids, Pennaria and Eudendrium, were found 

 to possess the same power. The dissociated cells 



