There are two points to this story: the first is the contingency of scientific discovery. Calwell was climbing the Ceratodus mountain when he seized the solution for the platypus puzzle. Frontiers may be unexpectedly contiguous. The fact that both questions interested the Cambridge embryological school made an opportunistic leap possible – but the coincidence was not really predictable. Despite the ‘pinnacle’ rhetoric, the discovery of platypus eggs by an uncontestable source, was to some extent an accident of circumstance. Caldwell was almost an accidental scientist, empowered (and burdened) by a large purse and high expectations. He was essentially charged with tasks of the post-Darwinian era, but his contribution to science was a final response to the challenge issued by Everard Home in 1825 to W. S. Macleay as he left for New South Wales: ‘what is principally wanted is the ova’.^[57] It is interesting that when Caldwell returned to Britain in 1887 with a Sydney-born wife, he maintained his Fellowship at Caius College Cambridge only nominally, and only until about 1889. He published very little and made his way as a successful Scottish paper-manufacturer in the family firm. It was left to others to undertake the anatomical work on his huge collections. Richard Semon in 1891, realising that Caldwell had barely begun this task, decided to make his own trip. Semon, by contrast, analysed all his specimens and published several important scientific papers as well as his popular book.^[58] But he too had great difficulties finding Ceratodus roe, because the part of the river he had chosen lacked the weed where the spawn is found. He found plenty of full grown ‘Djellah’, as the local Aborigines called them, and established that Ceratodus was no vegetarian, taking happily to meat and mollusc baits.^[59] Semon’s published scientific work, however, focused on the monotremes and marsupials, because he had successfully collected developmental series for these. There is no evidence that he observed the stages of growth in the living lungfish. Caldwell, by contrast, bred and displayed a young lungfish to the Royal Society of New South Wales in December 1884, but wrote no more about it after he returned to Britain.

The second story relates to the emergence of an opportunistic local Aboriginal science industry that underpinned the success of both Caldwell and Semon. Aboriginal collectors assisted many other scientific travellers including George Bennett around Yass and the Norwegian, Carl Lumholtz in Coomooboolaroo further west in Queensland, but on nothing like the scale required by both Caldwell and Semon. The demand for embryological series (collections with representatives of all stages of the growing animal) meant absolute carnage. For example, in a single season Caldwell’s team collected 1300-1400 echidnas ‘from which a fairly complete series of stages was obtained’.^[60] Such a vast exercise demanded a whole economy. Caldwell’s second season required 150 Aborigines working flat out for two months: ‘A skilful black, when he was hungry, generally brought in one female Echidna together with several males, every day … The blacks were paid half-a-crown for every female, but the price of flour, tea and sugar, which I sold to them, rose with the supply of Echidna. The half-crowns were, therefore, always just enough to buy food to keep the lazy blacks hungry’.^[61]

Semon tried to set up a base close to Gayndah, like Caldwell, but moved further upstream to a place outside Mundubbera, to get away from the pressures of the town. By contrast to Caldwell, Semon determined to pay his Aboriginal collectors fairly in cash at the end of each week:

They didn’t. ‘Never again in the whole of my campaign did I attain the good results of the first week’.^[63] Semon had reckoned without the opportunism of the frontier settlers. Mrs Corry, in that same week, set up an illegal operation to sell the cashed-up Aboriginal collectors booze. Despite the fact that she told Semon she was ‘very sorry and promised never to do it again’, he felt ‘ethically obliged’ to prohibit intemperance ‘at the cost of my own success, for I should certainly have been more prosperous had I kept to my first system of payment’.^[64] But Semon’s ‘fear of getting involved in serious difficulties’, and unwillingness to risk the ‘peaceable’ temperament of his Aboriginal team members, drove his decision to settle accounts at the end of the season. This was hardly humane concern for Aboriginal people, but rather a wish to protect the good name of science, to keep science on the civil side of the frontier. There is no doubt that both Caldwell and Semon were well aware that the quality of their science depended on the quality of their relations with the local Aboriginal communities. George Bennett, too, whose relations with his collectors in New South Wales were generally cordial by his own account, was conscious that ‘good Aborigines’ corresponded with good science. Bennett wrote in frustration to Richard Owen about the success of Caldwell, the young professional, in solving in a few months the mystery to which he had devoted half his life. ‘I had only two lazy aborigines’, Bennett complains ‘and Caldwell succeeds … encamped on the banks of the river … with the aid of a large number of aborigines. It is certainly the only way to insure success’.^[65] Bennett himself was not to blame for coming up with the ‘wrong answer’– only his ‘lazy’ Aborigines.

There is almost an intriguing suggestion here that where the scientific and settler frontiers coincide, the quality of the European observer is second in importance to the quality of Aboriginal assistance. This contradicts Kathleen Dugan’s contention that ‘the system of colonial science left scientists unable to collect biological information from the people best qualified to provide it’.^[66] The system veritably depended upon such people. The problem was the credibility of the brokers of the information, the settler naturalists. European science before Caldwell disbelieved Aboriginal and settler Australian voices alike. Settler Australian naturalists were deeply discomfited to find that their observations were worth no more than an Aboriginal’s. Indeed, the fact that Caldwell fresh from Cambridge with his well-paid Aboriginal team had established the ‘right answer’ without assistance from colonial scientists must have added to settler anxiety. This anxiety is manifest in the strategy of blaming Aboriginal assistants for wrong answers; settler naturalists wanted to be with civilization, on the side of empire and new knowledge, not with the colony, in error, and degenerating.