William Hay Caldwell’s Cambridge lineage was impeccable. The department he came from was leading the world in embryological research. He distanced himself from the ‘early days of Darwinism’ where ‘it was hoped to get a pedigree for every animal’. ‘Now that all biologists are Darwinists,’ he declared to the Royal Society of New South Wales on 17 December 1884, (where in fact there would have been very few Darwinian sympathisers!), ‘pedigree-hunting has gone out of fashion’.^[40] Perhaps he was aware of the lack of sympathy to Darwinian biology in Australia and letting the colonials know they were out of touch with the action. It is significant that he did not bother to write up this extempore talk. He left it to someone else (in all probability a colonial not sympathetic to Darwinian biology) to prepare a publication from his notes. Caldwell ultimately published so little that this account is crucial to gaining an idea of the state of his mind when in Australia. His work in morphology was to observe the minute differences between organic beings at various stages of development, in the belief that the patterns of evolution may be reflected in the patterns of individual development. His teacher at Cambridge, Professor Francis Maitland Balfour, had suggested in 1882 that Caldwell should consider travelling to Australia to work on the development of Ceratodus and ‘the peculiar Australian mammalia’. Balfour, elected to a Fellowship of the Royal Society aged only 27, was taught by Professor Michael Forster (no relation to the Forster of the fish, but an active member of the British Association, and Secretary of the Royal Society). Forster in turn, was taught by T. H. Huxley, Darwin’s most outspoken advocate. Caldwell benefited from the strong Darwinian lineage of Forster and Balfour at Cambridge, but it was also a burden to him.^[41] In 1882, Balfour, aged only 31, was killed in a mountaineering accident, and a travelling studentship was endowed in his memory. Caldwell, Balfour’s own student, working on a task assigned by Balfour, was the obvious first recipient of an ‘instrument by which [Balfour’s] memory was to reach beyond Cambridge and encompass the world for Darwinian biology’.^[42] Caldwell’s mission was well funded. In addition to a personal salary from the Balfour Trust, he brought with him grants totalling £500 from the Royal Society (of London) towards the cost of equipment. Both Cambridge University and the Royal Society eagerly awaited results.

George Bennett had studied the platypus mostly in New South Wales, and Caldwell, guided by this, determined to start in Sydney on his arrival in Australia in September 1883 and work over the platypus country inland. He had not counted on the skin-hunters. The trade in platypus skins had escalated dramatically in the two or three decades since Bennett’s trips. By late in the 19th century, platypus rugs of 40 or more pelts were being stitched together.^[43] ‘I wasted a fortnight trying to obtain information in Sydney as to where the animals were to be found in sufficient numbers for my purpose’.^[44] By mid-October, Caldwell had given up on platypus, and moved his attention to koala and wallaby, which were just beginning to breed. This material gave Caldwell new information on foetal membranes, and he sent home an account that was published in 1884 in the Quarterly Journal of Microscopal Sciences.

In April, Caldwell went north to the Burnett River district to find Ceratodus, and noticed when he arrived that as well as Ceratodus with ripe spermatozoa, both echidna and platypus were numerous in the area. He decided to stay there for the monotreme breeding season to try to get both Ceratodus and monotremes in the same year. ‘The Burnett district’, he wrote, ‘presented the further advantage of possessing a considerable number of black natives. I afterwards found that without the services of these people I should have had little chance of success’.^[45]

He set up under canvas out of Gayndah, realising that in order to work with Aboriginal people, he would have to create an independent camp with provisions, away from the town and stations, near the river where Ceratodus lived. This was probably on the advice of district squatters such as W. F. McCord, who gave similar advice to Semon seven years later. It was McCord who recommended ‘Frank’ an Aboriginal from Gayndah to Semon as ‘best adapted to act as an agent between me and the blacks, to explain my wishes to them, and to be of help in my searches for the desired animals’.^[46]

The curious travelling-scientist circus was appreciated by both blacks and whites in these districts where the economy was in a downward spiral. The wool industry was failing as the first good pastures had degenerated, and it was no longer possible to run sheep on the inferior regrowth pastures: ‘the survival of the unfittest’, wrote Semon wryly.^[47] Any new industry – even a passing science industry was embraced. It was probably no coincidence that the enterprising Frank recommended by McCord turned up on Semon’s coach from Biggendon to Gayndah, and became ‘the first black who crossed my path’. Semon came to have reservations about Frank, however, and ‘refused his services during my second stay in the Burnett.’^[48] The majority of workers in the new industry were Aboriginal, because of the particular skills required, but Caldwell reports that he employed some ‘white navvies’ to dig up platypus burrows (because the Aboriginal team was reluctant to do so). Semon also employed one of the local German farmers of the area to accompany him in the bush.

Caldwell revealed that his purse was well filled with his opening offer of £10 to ‘anyone who would show me Ceratodus spawn’. Once he had camp set up, he spent ‘many hours in the water’ in June and July hunting everywhere for the eggs of Ceratodus. Meanwhile:

This he described as ‘a lucky chance’.^[50] To kill a female platypus (which lay eggs in twos) at the point between laying eggs gave him the crucial information about the stage of development at which the eggs were laid – a stage he describes as ‘equal to a 36-hour chick’.^[51] The capture of this specimen is so absolutely crucial to the story, that it is interesting that he claims to have shot it himself. Perhaps he did. His timing was impeccable. On 29 August he sent in the telegram ‘Monotremes oviparous, ovum meriblastic’ to a neighbouring station. The telegram was delivered to Professor Archibald Liversidge at the University of Sydney, who in turn sent it to the British Association at Montreal. Less than a week later, on 2 September, Dr William Haacke from the South Australian Museum was able to give evidence of egg-laying in monotremes, displaying an egg from an echidna’s pouch, at a meeting of the Royal Society of South Australia.^[52] The Norwegian, Carl Lumholtz also claims to have heard reports of echidna’s eggs, and was in pursuit of them at the time he had to leave Australia, being convinced that ‘the reports I had received from the blacks corresponded with the facts’.^[53] Caldwell’s ability to tap the very consciously international audience in Canada – this was the first time that the British Association for the Advancement of Science had met outside Britain – was critical to his fame. The mystery was ripe for solution, but the telegram gave Caldwell a dramatic edge.

Caldwell himself hardly celebrated this historic moment. He was still anxious about that fish, and one can read in his words the pressure and burden that the Cambridge expectations and financial support had given him ‘Meanwhile I had never relaxed my efforts to find Ceratodus; but after four months I was beginning to despair of success’.^[54]

He finally found his Ceratodus eggs in September, and at this time employed some fifty ‘black retainers’. It was the women who were given the responsibility of trawling the river weed for Ceratodus, whilst the men collected echidna, a favourite food. ‘It was only occasionally, and then with great difficulty, that I persuaded them to dig for Ornithorhynchus. Not only the blacks, but their dogs, refused to eat the animal.’^[55] It is yet another paradox of the platypus that the mystery of its egg-laying habits was solved with the assistance of Aboriginal collectors who themselves had no reason to hunt for the animal. This contrasts sharply with the earlier experience of George Bennett with Goulburn Aboriginal collectors. Bennett writes:

But the Aborigines of the upper Burnett District, whose interest in platypus was minimal were the ones who assisted not only Caldwell, but also Semon in obtaining long embryological series critical to the debates in anatomy and morphology in the late 19th century.