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THE AMERICAN NATURALIST [Vol. LII 



While there has been a large amount of data obtained, 

 thus far no evidence shews that either a "reversal" or a 

 "slowing up" of the rotation may be produced in any of 

 the individuals utilized. 



Even though it may not be possible to change the direc- 

 tion or the period of rotation in "adult" forms, may not 

 such changes be produced in encysted forms or during a 

 period when gametes are developed. Experiments are 

 yet to be made with individuals in an encysted condition, 

 and with material available it will be possible to utilize 

 gamete-producing forms. That Euglena has a sexual 

 eyele was pointed out by the writer nearly ten years ago 

 (Walton, 1909). 7 Certain forms encyst, the cysts subdi- 

 viding to approximately a 16-cell stage, small flagellate 

 gametes emerge and conjugate. An experiment of this 

 nature involves a discussion of the environmental effect 

 on germ cells as compared with somatic cells, but does 

 not affect the issues with which we are concerned in the 

 present paper. 



There are many other questions of interest which arise 

 in a study such as outlined. For instance, what has been 

 the origin of the stria 1 which are much specialized in many 

 forms, although entirely absent in other forms (Fig. 4) so 

 far as visibility with the microscope is concerned. The 

 majority of the positive northern forms have "left- 

 handed" stria", a smaller number have longitudinal 

 striae, while a considerable number appear to have no 

 stria?. None have been found with "right-handed" 

 stria?. At first one may be inclined to attribute such "a 

 character to natural selection, but when one commences 

 to ascertain the value of the character on the basis of pro- 

 gression, rotation and axial angle, such a conclusion 

 seems less certain. There are a few facts that appear 

 evident. First that the development of the striae has 

 been at a considerably later period than that of the rota- 

 tion direction. Second that the relative position of the 

 stria? has been largely dependent on the rotation. Third, 



-Paper presented at annual meeting of Ohio Academy of Science, 1908. 



