910 



SCIENCE 



[N. S. Vol. XXVII. No. 702 



ing point of the same organisms which fur- 

 nished the enzyme, diastatie ferments are 

 nearly or completely inactivated and their 

 activity increases as the concentration of 

 CuSO, diminishes. Whether the same cor- 

 relation exists with other enzymes and 

 whether the cell bodies absorb and concen- 

 trate the CuSO^ from dilute solution, is 

 still under investigation. 



Minimal Size in Form-regulation: C. M. 



Child, University of Chicago. 



The minimal size of pieces capable of 

 complete form-regulation in a given 

 species is not a constant quantity, but 

 varies according to the region of the body 

 involved and in some species with age. It 

 may also vary to a certain extent with 

 the physiological condition of the indi- 

 vidual. 



In Tuhularia and Corymorpha, for 

 example, a much larger piece is necessary 

 for the formation of a complete hydranth 

 and stem in the distal region of the 

 original stem than in the proximal region. 



In Planaria maculata a piece from the 

 middle region of the body must be much 

 larger than one from the terminal regions 

 to produce a complete animal. 



Similar differences are found in various 

 other species of coelenterates and turbel- 

 laria. 



As regards age differences, the minimal 

 size of pieces capable of producing a com- 

 plete animal is relatively greater in newly 

 hatched specimens of Planaria simplicis- 

 sima than in adult animals, though as 

 regards actual size the reverse is the ca.se. 



Evidently, then, minimal size in these 

 species is not simply a matter of a certain 

 number of cells or a certain constant 

 amount of living material, but is de- 

 pendent rather on the position and func- 

 tion of the parts in the original whole. 

 We may probably go a step farther and 

 assert that it is primarily dependent upon 



the rapidity of physiological or functional 

 changes with change of level in the whole. 

 Where this change is relatively rapid a 

 piece of given length is physiologically 

 more nearly a complete system than a piece 

 of the same length in a region or at an 

 age where the change from level to level is 

 less rapid. 



These facts constitute strong evidence 

 against the cell theory in its more special 

 form, for the number of cells may differ 

 very widely in minimal pieces from dif- 

 ferent regions. They point to correlation 

 between parts as the essential feature in 

 regulatory and probably also in normal de- 

 velopment—at least in certain stages. 



Galvanotropism of Bacteria: J. F. Abbott, 



Washington University. 



It being ordinarily understood that bac- 

 teria do not respond to the influence of a 

 galvanic stream too weak to kill them, it 

 seemed important to determine whether 

 this be really so ; and second, to determine, 

 if a tropic response be obtained, in how 

 far this might be altered by change in 

 environmental conditions. 



Results of extended work on B. termo 

 and B. suhtilis demonstrated without any 

 question that pure cultures of these bac- 

 teria gather under the influence of very 

 weak currents at the cathode and follow 

 repeated reversals of the poles. 



Pure cultures grown in acid-modified 

 and alkali-modified peptone-gelatin ap- 

 peared to respond in most cases, though 

 not in all, in opposite manner, alkali cul- 

 tures gathering at the cathode and acid 

 cultures at the anode. 



These results seem to be in harmony 

 with those of Greeley on Paramecium and 

 give color to the conception that the gal- 

 vanotropic response may be due to, or di- 

 rected by, the physico-chemical constitu- 

 tion of protoplasm. 



Work along this line is being continued. 



