32 A. J. GOLDFARB. 



I 



(c) Single giant larvae may develop when only one gut was 

 differentiated and only one axis formed in the double gastrula. 



(d) Single giant larvae may develop when both guts are differ- 

 entiated and both axes are known. 



(e) When these axes are clearly and definitely NOT PARALLEL 

 AND NOT SYMMETRICAL the pair nevertheless gave rise to single 

 giant larvae. 



(/) Vice versa, when the axes were parallel single giant larvae 

 were not developed, but various types of double fused larvae. 



3. It was ascertained that the axes of the two fusing members 

 are frequently shifted and rotated towards or away from blasto- 

 meric symmetry and with a remarkably large range of movement; 

 that this shifting towards symmetry had no effect upon the 

 formation of single larvae; and finally that this rotation of the 

 axes did not affect the polarity of the fusing members. 



4. The history of the changes in fused members showed that 

 Riesenlarva may be formed when two fusing eggs are not blasto- 

 merically symmetrical; that a complex series of changes take 

 place independent of such symmetry; that these changes are 

 associated with an inequality in the two grafted members, an 

 inequality in size or rate of differentiation, or vigor; that there 

 is a definite tendency for the smaller or slower or less vigorous 

 member to be suppressed in its development, that part or the 

 whole of this member may be absorbed, that a translocation of 

 cells may take place and may develop accessory parts or form 

 enlarged organs in the dominant member. That with starvation 

 there occurs a partial or complete absorption of accessory parts, 

 and reduction in size of the larva. The result of these com- 

 plicated series of regulatory changes is sometimes the formation 

 of a single giant larva, or a single normal size larva, which, if 

 its history were not known, could not be distinguished from 

 control larvae. 



