Glasgow came back from 34-0 down at half-time to secure a bonus point in their Heineken Cup match against Toulon. Photograph: David Rogers/Getty Images  In the dense, often impenetrable, pages of the guide to playing in France, one of the more fanciful chapters is devoted to "gaining a bonus point by scoring four tries". The key to emerging with something from the most hostile environment – with apologies to Thomond Park – in the sub-international game is the very opposite of the standard text on how to survive the Mayol, the Aimé Giral, the Marcel Michelin and all those other quintessentially French stadiums.  In such places the accepted theory for visitors is to stick together, battle against the odds and the onslaught, and hope that after half an hour you are still in the game. If you are, you have a chance of going home with a bonus point for losing by seven points or fewer. The four-try option is even harder to plan: let the onslaught bury you and when it is over and you find yourself beaten, you hit back and prosper in a carefree romp.  It was the Glasgow way against Toulon at the Mayol, interred by the defending Heineken Cup champions of Europe in a display that was as cruel as it was ultimately incomplete. Toulon did not bury Glasgow deep enough, and out popped the Scots in the second half to rescue a spoil. It was a remarkable resurrection.  Take a point from an away fixture and your campaign remains very much on track. And now Glasgow have a chance to build on their unlikely base. They are at home on Sunday against Exeter, who did something of a Toulon of their own in round one, piling the misery on the Cardiff Blues for a full half and a bit before letting the Welsh region escape with a four-try bonus point.  Whether Glasgow have truly recovered their wits remains to be seen. They will have been tempted to dwell exclusively on their comeback as they prepare for the well-drilled and tight-knit Chiefs, but perhaps their coach, Gregor Townsend, will have forced them to suffer the painful bits again. Fear can be a wonderful tool for a rapid recovery. Can Exeter maintain their form and timing, now that their class has been revealed? To be a known entity, rather than the surprise package, alters the dynamic.  It may be suspected that this will be anything but the romp suffered by the one and enjoyed by the other in round one, and that it will be a bonus-point affair down the more conventional seven-point route for the loser. Perhaps with Glasgow the winner.  Northampton came away from another of those intimidating French stadiums – the Pierre Antoine in Castres – with the losing bonus point, the defiance of convention being that their visit might have been even more productive. The Saints seemed to be in control of the game against the defending Top 14 champions of France and then gifted a breakaway try. It was all a bit the wrong way around, but it means that Northampton are still in the chase and at home against the Ospreys, who emerged with nothing from their home tie against Leinster.  To lose at home without a bonus point is to impale the hopes of the season on the sharpest of spikes. Defeat for the flag-bearing Welsh region has peeled back the scab over the reality of Welsh rugby below the dream world of the Six Nations and the Lions tour. Up there no wrong can be done; in region-land it is agony, with no settlement in sight, no money to bring to the table, no vision of what may one day be …  It could be said that it is inevitable, given the historical form of leading players in the early part of seasons following a Lions tour, that the Welsh teams will struggle. But if a lack of precision was forgivable, the lack of all-round incision suggested that the Ospreys are finding it difficult to move on after the retirement of Shane Williams and the departure of Kahn Fotuali'i. A clearer picture will emerge when the scrum-half faces his old side at Franklin's Gardens – clearer or possibly darker, with another layer of shade applied to the land he left behind.  Like the Ospreys, Harlequins lost at home in round one, albeit with the crumb of a losing bonus. If the Welsh region must bounce back away in England, the Quins must go to one of those French fortresses – the most impregnable of them all, the Marcel Michelin in Clermont-Ferrand. Quite how Clermont lost in Paris to Racing Metro 92 is presumably still exercising them. Irritation is a mean way to guarantee a return to winning ways in their cherished citadel.  Perhaps it may be time to try the Glasgow approach: go for broke when the storm has blown itself out. Quins have tried it before, spectacularly in Toulouse. Mike Brown in current form may score four tries on his own. It could be the tie of the day.  Edinburgh, victors over Munster in round one, have to ply their own route south, to Perpignan. L'USAP (Perpignan) are not quite at their ferociously Catalan most confident. There is a chance that Edinburgh, bottom of the Pro 12, could defy domestic form and go on one of their Euro runs to the knockout stages. Celtic cool, and which really, really annoys the English and the French. As such, it may also have a place in the guide to surviving or suffering on the rugby fields of France.
Eddie Butler: Glasgow's comeback against Toulon shows that taking a point in defeat can keep your campaign on track