306 G. E. COGHILL 



EXPLANATION OF FIGUUES 



All of the figures are taken from Amblystoma puuctatum Cope, excepting 

 figure 71, which is from A. microstomum Cope, and figures 11 and 12, which are 

 from another species of Amblystoma, probably jeffersonianum. 



Methods. The methods followed in the preparation of Nos. 444, 449, 467 and 

 473 were described in Paper I. In Nos. 543, 54G, 545, 550, 557 and 593 the fixa- 

 tion was with Van Gehuchten's fluid, and staining with erythrosin and toluidin 

 blue. For No. 455 fixation was with formol-Zenker solution; staining with 

 Bomer's haematoxylin and slightly acidulated orange G. For Nos. 561, 562 and 

 567 fixation was with Zenker's solution and staining with iron haematoxylin and 

 orange G., excepting that the latter was omitted in No. 567. For 447 and 496 

 the fixation was with corrosive sublimate-acetic acid mixture and staining with 

 alum cochineal (447) and alum carmine (496) in tof.o with Lyon's blue in 95 per 

 cent alcohol on the slide. No. 635 was prepared with Paton's silver method: 

 neutral 10 per cent formalin about three months [formalin (40 per cent formal- 

 dehyde) is saturated with sodium carbonate or lithium carbonate and the fixing 

 fluid is made by mixing one part of this stock solution with nine parts of distilled 

 water]; washed in running water over night; f per cent silver nitrate five days 

 and four hours; f per cent nitrate of silver to which four drops of sodium 

 hydroxide have been added for every 20 cc. of the solution, and then about 

 twelve drops of ammonia, two hours; bath in distilled water to which one 

 drop of glacial acetic acid has been added for every 2 cc, twenty minutes; 

 1 per cent freshly dissolved hydrochinone, sixteen hours; washed in distilled 

 water; dehydrated through graded and absolute alcohol in about 6f hours; 

 cleared and embedded through cedar oil, cedar oil one part and paraffin one 

 part, cedar oil one part and paraffin two parts, then pure paraffin, in two 

 hours or a little less. My experience is that this method of clearing and embed- 

 ding is very satisfactory in use upon amphibian embryos, in which the yolk is 

 a very refractory element. The silver-impregnated material does not suffer 

 from treatment with cedar oil for a day or more. 



ABBREVIATIONS 



Ad., area of adhesion between the skin Ent., the point of entrance of the nerve 



and ganglion or otocyst as indicated indicated into the brain 



Aud.V., the auditory vesicle or otocyst Fas. sol., the fasciculus solitarius 



c, the branch of the n. mandibularis V g, ramus lingualis of the glossopharyn- 

 to the balancer geal nerve 



d, ramus palatinus VII G.G., the Gasserian ganglion 

 DC, the Rohon-Beard cells of the spinal G.gen., the geniculate ganglion 



cord and cells of like character in the G. Jug., the jugular ganglion of the 



brain vagus 



DT, the dorsal sensory tract of the G.L.L.VII, the lateral line ganglia of 



spinal cord and its extension into the the facial nerve 



brain G.L.L.IX, the lateral line ganglion of 



e,n. hyomandibularis VII the glossopharyngeal nerve 



Ec.Th., thickened regions of ectoderm G.L.L.X, the lateral line ganglion of 



End., the endolymphatic appendage the vagus 



of the otocyst 



