Vol. XXXII. April, igij. No. 4 



BIOLOGICAL BULLETIN 



EXPERIMENTAL ALTERATION OF THE AXIAL 



GRADIENT IN THE ALGA, GRIFFITHSIA 



BORNETIANA. 



C. M. CHILD. 

 (WITH 15 FIGURES.) 



The existence of axial gradients in susceptibility to various 

 agents and conditions has been demonstrated as a characteristic 

 feature of axiate animals, and the relation of such gradients on 

 the one hand to metabolic and protoplasmic condition and on 

 the other to the morphological and physiological order or pattern 

 characteristic of development has been discussed in various 

 publications. 1 The results of these investigations on animals 

 led to the attempt to determine whether similar axial gradients 

 occur in plants and some of the data on algae have already ap- 

 peared (Child, 'i6r, 'i6e, '17). The existence of such gradients 

 in the axes of at least certain plants as well as in the axes of 

 animals being demonstrated, it remains to determine their rela- 

 tion to the order or pattern of the plant axis. To accomplish 

 this completely it would be necessary to obliterate or reverse 

 existing gradients, to determine experimentally the origin of 

 new gradients and to observe the effect of such changes upon 

 order or pattern in the plant body. 



Obliteration and reversal of axial gradients in algae by various 

 means have already been described (Child, 'i6e, '17). In most 

 cases these changes represented a stage in the process of dying, 

 and while they showed that changes might occur, the fact that 

 these changes were soon followed by death made it impossible 



1 See Child, '150, Chap. IX., '15^, 'isc, 'i6a, 'i6b, '160, 'i6d. Hyman '16, and 

 references to further literature in these publications. 



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