260 



TRANSPLANTATIONS 



3. The gill swelling will be found in a line with the eye but beneath the first several 



somites. Its anterior extremity will be just posterior to the otic vesicle. With oper- 

 ating glass needle and hair loop cut out the entire gill swelling, and include mesoderm 

 and some of the pharyngeal endoderm. Keeping the piece intact, and properly oriented, 

 transfer it on a needle to the prepared site on the host. Further excavate the host 

 site to hold the transplant, and then hold it in place for 30 nninutes by means of a 

 coverslip bridge. Remove the bridge carefully, and clean away any sloughed off 

 cells around the nnargin of the wound by means of a hair loop. After complete heal- 

 ing transfer to the growing medium. 



Variations in the above procedure not only include a different site on the host, but isola- 

 tion of the germ-layer constituents of the anlage' to determine (if any) their separate abil- 

 ity to develop into gills; rotation of the anlage; and xenoplastic transplants between the 

 slow developing species (A. punctatum) and the rapidly developing species (A. tigrinum). 



Make drawing or photographic records of individual transplants at appropriate intervals. 



DORSAL VIEW 



VENTRAL VIEW 



HETEROPLASTIC TRANSPLANTATION OF LIMB FROM A. TIGRINUM 

 TO RIGHT SIDE OF A. PUNCTATUM 



