The Journal of experimental zoology . coid grows out in an antero-ventral direction andbecomes a structure very similar in shape to the procoracoid ofNecturus. The coracoid, which comprises the greater part ofthe ventral zone of the girdle, is a large flat rounded plate ofcartilage lying ventral and posterior to the procoracoid. Thetwo coracoids overlap in the mid-ventral line. The shape of theventral portion of the adult girdle is very similar to that figuredby Fiirbringer (73) for Salamandra maculata. SHOULDER GIRDLE AND ANTERIOR LIMB 503 No description of the shoulder muscles of Amblystoma
The Journal of experimental zoology . coid grows out in an antero-ventral direction andbecomes a structure very similar in shape to the procoracoid ofNecturus. The coracoid, which comprises the greater part ofthe ventral zone of the girdle, is a large flat rounded plate ofcartilage lying ventral and posterior to the procoracoid. Thetwo coracoids overlap in the mid-ventral line. The shape of theventral portion of the adult girdle is very similar to that figuredby Fiirbringer (73) for Salamandra maculata. SHOULDER GIRDLE AND ANTERIOR LIMB 503 No description of the shoulder muscles of Amblystoma couldbe found in the literature. The musculature, however, so far ashas been studied, closely resembles that of Salamandra macu-lata, a European tailed Amphibian described by Ftirbringer (). In referring to the musculature, Fiirbringers nomencla-ture will be employed. 3. EXPERIMENTAL The experiments were carried out upon embryos in two dif-ferent stages: a) the so-called tail-bud stage, and b) the stage ofopen medullary Fig. I Camera-lucida drawing of an embryo of Amblystoma in the tail-budstage. The larger of the two circles represents the typical limb disc. X , = pronephros. 1. EXPERIMENTS ON EMBRYOS IN THE TAIL-BUD STAGE (STAGE 29) A. Extirpation experiments 1. Reinoval of the suprascapula rudiment. As has alreadybeen pointed out (Harrison, 15), the fore-limb rudiment of anembrj^o in the tail-bud stage consists of a somatopleural thick-ening just ventral to the pronephros, centering in the region ofthe fourth myotome and extending over into that of the third andfifth. The formation of a suprascapula following the extirpationof the limb rudiment in this stage shows that its rudiment is notincluded with the limb mesoderm. Although there is ho visiblesuprascapula rudiment, nevertheless, extirpation of the regiona-e X 1-3 (text fig. 1), including the outer or cutis layer of the 504 S. R. DETWILER TABLE 1 Shoioing the results following the removal of the area
Size: 2051px × 1219px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwi, bookcentury1900, bookdecade1910, booksubjectzoology
