VITAL STAINING AND MORPHOGENETIC MOVEMENTS 



209 



path of the dye as it moves posteriorly with the development of the lateral line system. 

 The dye should pass posteriorly across the somites, and subsequently a smaller line 

 may be seen passing dorsal to the somites, both reaching the tail (see Stone, 1933). 



Specific Organ Anlagen: Consult the accompanying figures and photographs for the 

 presumptive areas for the nasal placodes, balancers, lens, gills, etc. (also see 

 Carpenter, 1937) and stain any specific area to check the "fate-maps" that have de- 

 rived by this procedure. 



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Fig. 1. Camera -lucida drawing of Q living Amblystoma punctQtum embryo, mode 1 day after operation. Nile-blue 

 stained graft (shaded) as excised from the same area in the donor <\% it now occupies in the recipient. The 

 operation was made at Harrison stage 30. The specimen is now about stage 31. For following stages see 

 Figures 2, 3, and 4. 



Fig. 2. Same living specimen as in Figure 1, shown second day after operation. The shaded elongated club-shaped 

 structure growing posteriorly from ectoderm of graft (shaded) is the blue migrating mid-body lateral-line 

 primordium. Specimen is about stage 36. 



Fig. 3. Same specimen ai in Figures 1 and 2, shown third day after operation. Note beaded appearance of mid-body 

 line primordium which has left in its trail blue clumps (shoded) of cells that are forming lateral-line organs. 

 The short primordium of the dorsal body line (above limb region) from the graft is also laying down segments 

 for sense organs. Ectoderm of graft (shaded) is still seen above second and third gill buds. Specimen is 

 stage 37. 



Fig. 4. Same specimen as in Figures 1, 2, and 3, shown fourth day after operation. Mid-body line primordium has 

 bent doreally (the normal course) above and behind anal region and has moved caudally on the tail. The 

 tear-shaped dorsal body line primordium (second portion of figure) has not quite reached the position dorsal 

 to the anal region where it normally terminates. It did so later. The blue mid-body primordium, about 

 3 days later, reached the tip of the tail and laid down a terminal blue organ at Harrison stage 44 (a larva 

 with bidigitate fore limb and open mouth). Note in organs the dark ring about a light center and a peri- 

 pheral light border. For a later stage see Figure 13. Specimen is stage 39. 



Development of the lateral-line organ system a% indicated by Nile Blue Sulphate -stained graft of the anlage. 



(From Stone, 1933: Jour. Comp. Neur. 57:507) 



