Maech 26, 1915] 



SCIENCE 



471 



Avian thyroid 222.0 



Control 43.6 



Mammalian thyroid 315.3 



Control 57.3 



The conclusion is that throughout the evolution 

 of the vertebrate phylum, the thyroid has retained 

 certain of its physiological characters intact. 

 The observations previously made by Nowikoff, 

 later by Shumway, on mammalian thyroid influ- 

 ence on Paramwcium are thus confirmed, and the 

 significance of the facts extended so as to include 

 the homologous glands of each of the other four 

 classes of vertebrates. 



The Effect of the Bemoval of the Marginal Sense 



Organs on the Sate of Regeneration in Cassiopea 



Xamacana: Lewis E. Gabt. 



The results of the investigations of most work- 

 ers on regeneration has shown that no direct effect 

 of the nervous system upon regeneration could be 

 demonstrated. Zeleny concluded as a result of his 

 work on Cassiopea that when the sense organs 

 were removed the animals regenerate sometimes 

 faster and sometimes slower than do specimens 

 with the sense organs intact. Stockard removed 

 the sense organs from one half of a Cassiopea 

 disk and insulated the two halves by removing a 

 strip of sub-umbrella tissue so that one half was 

 active, the other inactive, and found that the 

 rate of regeneration was the same in both halves. 

 From these experiments he concluded that muscu- 

 lar activity had no influence on the rate of re- 

 generation. 



In a large series of experiments on Cassiopea 

 disks prepared in the manner just mentioned I 

 have obtained the following results: 



1. When entire disks are used for the experi- 

 ments those from which the sense organs have 

 been removed may regenerate slower or faster than 

 those retaining their sense organs on account of 

 individual variation in the rate of regeneration. 



2. In specimens prepared so that one half is 

 active, the other inactive, the active side (that 

 bearing the sense organs) always regenerates 

 fastest. The difference in rate is particularly 

 noticeable in earlier stages of regeneration. 



3. When the sense organs are removed from 

 one half of the disk, but the halves not insulated, 

 the rate of regeneration is the same for both 

 sides. If only a single sense organ remains the 

 results are the same. 



4. In a solution made up of sea water to which 

 has been added 15 volumes per cent, of 0.6 M 



MgSOi the regeneration is equal from both sides, 

 but at the rate of the inactive half of a specimen 

 from which one half the sense organs have been 

 removed. 



5. In specimens from which all sense organs 

 have been removed but in which one half is kept 

 in pulsation by means of a trapped wave of con- 

 traction, the regeneration is the same for both 

 halves, although the rate of contraction in the ac- 

 tive half may be higher than for a half disk on 

 which the sense organs are present. 



The rate of metabolism as determined for the 

 writer by Dr. S. Tashiro is higher for the half 

 disk bearing sense organs than for the inactive 

 half, or for the half that is kept in contraction by 

 means of a trapped wave. 

 The Locomotion of Actinians: G. H. Parker. 



The creeping habits of Metridium and Sagartia 

 were studied at Woods Hole and of Condalaotis 

 and Actinia at Bermuda. Metridium and Sagar- 

 tia creep slowly and in directions which may be in 

 one individual at right angles to its axis of struc- 

 ture, in another coincident with it, and in still 

 another oblique to it. Whether one individual 

 could assume in sequence all these directions was 

 not ascertained for these sea anemones. In 

 Condalactis and Actinia the creeping was more 

 actively carried out than in Metridium and Sa- 

 gartia. A single Actinia crept now In the direc- 

 tion of its axis, now at right angles to it, and 

 now in some other direction. There is no reason 

 to suppose that this freedom is not possessed by 

 the other sea anemones. In all the forms studied 

 locomotion was accomplished by a wave-like move- 

 ment of the foot. This began at the rear edge of 

 the foot and proceeded to the front edge. It was 

 exactly like the direct type of wave seen in the 

 mollusk foot, but could be established temporarily 

 on any axis. In Condylactis it required about 

 three minutes for a wave to pass over the foot 

 and with each wave the animal progressed a little 

 over a centimeter in distance. 



The Behavior of an Enteropneust : W. J. Crozier. 

 A species of Ptychodera found in Bermuda was 

 studied with reference to its movements and sen- 

 sory reactions. The orderly progression of peri- 

 staltic waves on the thorax and abdomen was 

 found to depend upon the continuity of the dorsal 

 and ventral nerve cords. At night the animal re- 

 sponded to general mechanical stimulation by the 

 emission of a phosphorescent material from the 

 collar region. Ptychodera showed "differential 

 sensitivity" to light; it was not photographic. 



