. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE REPRODUCTIVE CYCLE 399 eleven humpback whales taken in February which is higher than that for Chittleborough's sample. In fact the maximum diameter they found was 290 11 which seems very high, but their sections were cut from frozen material without embedding, so the shrinkage would be expected to be much less than in paraffin-embedded material. We are comparing here anoestrous fin and humpback whales with humpback whales in rut and one would expect the latter to show much higher values with
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE REPRODUCTIVE CYCLE 399 eleven humpback whales taken in February which is higher than that for Chittleborough's sample. In fact the maximum diameter they found was 290 11 which seems very high, but their sections were cut from frozen material without embedding, so the shrinkage would be expected to be much less than in paraffin-embedded material. We are comparing here anoestrous fin and humpback whales with humpback whales in rut and one would expect the latter to show much higher values with identical treatment. In pinnipeds of at least four widely different genera the tubule diameters in rut are about 220 11 and shrink to less than 140^ in anoestrus (Laws, 1956c, fig. 7; McLaren, 1958, fig. 3; Mansfield, 1958, fig. 15). The antarctic fin-whale material suggests that there is a similar range in whales. In this material anoestrous tubules are about 140// in diameter (Text-fig. 28) and the largest measured (241 11) was either approaching rut or taken immediately 250 200 150 100 0 510 15 2005 O FREQUENCY IO 15 20 Text-fig. 29. Measurements of seminiferous tubules. A, humpback whale, West Australia; B, fin whale, South Africa; C, fin whale, antarctic; D, E, and F, means ± 20- and for antarctic fin whales classified as to diatom infection; D, recent arrivals; E, heavy diatom infection, South Georgia; F, heavy infection, antarctic pelagic. It seems probable then that the fin-whale material from South Africa and the humpback-whale material from Australia has undergone much greater shrinkage than the antarctic material, so that the testis tubule diameters cannot be directly compared. It is also possible, however, that the South African material gives a true picture, relative to the antarctic material, and that there is a decrease in average tubule diameter from July to September, followed by an enlargement associated with the southward migration. This possib
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