Fathoming Jellyworks is like trying to wrestle with a mound of the wobbly, kids' party staple itself.

The miracles needed for the firm to justify its 20-fold share rise and £200 million price tag are enormous enough. For new investors to profit, returns on its investments will have to be more spectacular than hedge funds' wildest dreams. And Guinan and Rowland will have to show near-superhuman foresight by investing early and cheaply in sure-fire winners.

Each time they put money into other Internet investment funds, you're only backing their judgment of other people's nous. So the likely returns diminish exponentially. Three of Jellyworks' biggest investments are in other 'incubator funds': Antfactory, WorldCap and Grand Central Holdings.

But why not ask, instead, whether you know exactly what Jellyworks already has. The answer is a resounding 'no' - it refuses to disclose the size of its stakes, and the prices paid per share, in all its investments. Last week chairman Edward Guinan said he would come back to us on these and other specifics, such as when precisely the Rowland family took each of its stakes. He never did.

Evaluating the prospects of each firm is hard enough (much of Matchnet's dating website, for example, is still 'under construction'). But without this basic data, you can't tell what stake Jellyworks has in their success.

Jellyworks' start-up structure is also confusing. The Observer asked Guinan why it had taken an option over the Rowland family's investments. Why not simply put them in Jellyworks from day one?

'The accountants' attorneys raised questions,' he said. 'It would have had to go to the valuers. It was suggested the simplest way was to create an option. It [the alternative] looked as if it would add £50,000 to the costs. It would have taken lots of time, with people running round for days over Christmas.'

There are other niggles. First, the sudden change of mind on domicile: between the AIM admission notice on 6 December and the prospectus eight days later, the firm switched from Guernsey to the UK. Three (presumably Guernsey-based) non-executive directors were dropped in favour of one non-exec, Ashley Ward of Orchestream. The vehicle for the Rowland family holding also changed.

Second, the exercise of 831,000 options in lieu of fees by Jellyworks' advisers, Fiske and Nabarro Wells. Unlike other locked-in investors, Guinan says, the advisers have been free to deal since. How many shares, you may ask, have they sold?

A third is Guinan's own purchase of 150,000 Jellyworks shares at between 50p and 52p. That came a day before the firm's surprise investment in Grand Central and a £1m placing of Jellyworks shares at 60p each. Guinan's buying was seen as a sign of confidence, and the shares shot up. To spend £75,000 on stock and see the value of rest of your shares and options rise by £6m is a very profitable way to show confidence.

Jellyworks would dismiss this as nitpicking. But it is the impossibility of ascertaining the stakes Jellyworks has that defeats valuation. You have to believe that the prices others will pay will spiral higher than whatever it paid. You have to suspend your belief not only in human fallibility, but in gravity itself.