I3O BRUCE D. REYNOLDS. 



experiment was stopped on Nov. 1st. line k had undergone 119 

 divisions and line kd 122. 



The results obtained in the above experiments indicate that 

 the changes produced in the protoplasm of related individuals 

 reproducing vegetatively, are at least greatly influenced by the 

 environment in fact to such an extent that two lines which have 

 been negative to each other's protoplasmic fragments for several 

 weeks can be brought back to a common condition in which cross- 

 fusion will take place between them within approximately 20 

 days. However convincing this evidence seems, it was con- 

 sidered advisable to obtain further proof. To that end, a series 

 of experiments was planned which wouki extend the observa- 

 tions over a longer period, and at the same time remove any 

 question as to the identity of the environments in which the two 

 lines of a clone were existing. It is a matter of common knowl- 

 edge, that when Arcella divides the newly formed shell is lighter 

 in color than the old shell, and that this difference in shell colora- 

 tion continues for some time after division takes place. There- 

 fore an individual possessing a dark shell was taken from each, of 

 the two diverging lines of a given clone and placed in the same 

 concavity. Then daily examinations were made, and when two 

 specimens with light-colored shells appeared, they were removed 

 and tested for inter-protoplasmic reactions; while the two dark- 

 shelled organisms were transferred to fresh culture medium. It 

 might be said in this connection, that the morphological differ- 

 ences between specimens from the two lines, were usually also 

 great enough to enable a careful observer to distinguish one from 

 the other. 



On November I, 1922, four experiments of this type were 

 started, involving clone J, line j-124 and line jd-ii9; clone K, 

 line k-135 and line kd-132; clone Q, line q-65 and line qd-65; 

 and clone R, line 1-58 and line rd-58. The two lines of each of 

 these clones had previously been brought to a common condition 

 1>\ exchanging small quantities of culture media from one to the 

 other, as described elsewhere; so that individuals from one line 

 would fuse with fragments of members of the other at the begin- 

 ning of these experiments. So then, it was to be expected that 

 the immediate progeny of two such organisms would also exhibit 

 the cross-fusion phenomenon. 



