. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 388 DISCOVERY REPORTS other, and as regards humpback whales to the divergence of the results of Chittleborough (1955 6) and Symons and Weston (1958). It is thought that the techniques used by the 'Discovery' Committee and later by the National Institute of Oceanography have been fairly well standardized and that in the present material individual differences in interpretation are reasonably small. There is, however, a basic cause of variation which must now be mentioned. Fusion of the epiphyses
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 388 DISCOVERY REPORTS other, and as regards humpback whales to the divergence of the results of Chittleborough (1955 6) and Symons and Weston (1958). It is thought that the techniques used by the 'Discovery' Committee and later by the National Institute of Oceanography have been fairly well standardized and that in the present material individual differences in interpretation are reasonably small. There is, however, a basic cause of variation which must now be mentioned. Fusion of the epiphyses to the centrum progresses from the centre to the periphery (Text-fig. 24) which means that the determination of the state of fusion depends to some extent on the depth at which the line of fusion is examined and is, therefore, influenced by the tools used to examine the vertebrae. When a knife is used the cut is necessarily superficial; with a hand-axe or adze the cut is deeper, but more superficial than the section exposed by use of a felling axe. Other things being equal, the more superficial the examination, the later will be the apparent attainment of physical UTC UTC UFC FJV FJI Text-fig. 24. Diagram showing stages of epiphyseal fusion. Above, sagittal section of centrum and epiphysis; below, appearance of tangential chips. The first example of FJI shows how the blood may indicate the line of fusion. Results In analysing the data, certain simple conventions have been followed. (a) As regards the classification of individual vertebrae, fused join visible (FJV) is counted as fully fused. Although the fact that the join is visible means that there is a thin layer of cartilage at the periphery, this layer is not always continuous ( Wheeler, 1930, PI. V, fig. 2) and usually there is com- plete fusion in the less superficial parts (Text-fig. 24). Purves and Mountford (1959) have mistakenly assumed this class to be unfused, but have used the figure of 14-15 corpora
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