That’s it! I am done with segments. In the experiment last week, segments from red-light-grown Sliver Queen mesocotyls behaved like those from the UK-maize. Variably. Another potential magic bullet misses the target. OK then: I have tried growing seedlings under red light, instead of in darkness, tried allowing an hour in water before adding auxin, and tried another genotype. None of these trials brought the variation between individual segments down to a manageable level.

It is time, arguably long past time, to let go. The point of this saga was to develop a convenient system for doing segment-growth experiments. The image analysis part of that made sense, and still does. Working in darkness was inconvenience cubed but the fastest growth gives the widest range to see changes. Indeed, mesocotyl segments from dark-grown seedlings elongated around twice the rate of segments from red-light-grown plants, a rapidity that made the irregularity of the response among segments alarmingly obvious. Variability was brought under control by the simple expedients of neither red light nor pre-incubation. A convenient and reliable segment growth system remains out of reach.

What did the old timers do that I didn’t? Who knows? Maybe variability bedeviled those experiments too and was just averaged over? Maybe I needed abrasion (another feature of the classic work was abrading the cuticle to increase permeability)? Probably, if I pecked away at this detail and that, a tractable experimental system would emerge. But doing so goes far beyond any rational definition of convenient, at least to get from here to there. Plenty of other experimental systems in the sea.

And last week, I tossed into the water an entirely new lure. The new experiments will be on root growth. To get them started, I rearranged the gear in the red room. First, I packed up the washer dishes and the little jig that holds the razors for cutting short segments reproducibly. The coming experiments will measure the kinetics of root growth and the experimental unit will be a square Petri plate. So, I reoriented the camera and trained it on a such a plate, positioning things to fill the field right up to the edge. To unlock and focus the camera lens, I had to go track down an Allen key, which had gone to Basingstoke. To go further, to get the exact focus, and to adjust the infrared light source to best effect, I need a plate with roots.

To that end, on Friday, I set up some maize seeds in a jelly roll. Hmm, I should have taken a snap. These jelly rolls are made like this. Cut a 10 inch by 3 inch strip of germination paper (think super thick and absorbent paper towel) and overlay a stiff brown not particularly absorbent paper towel. Wet well. Then, put down a row of seed running along one of the long edges with the place where the root will emerge (this is visible on a maize seed) pointing away from that edge. Finally, after overlaying and wetting another brown paper towel, roll the assembly up. This makes maybe more of a swirly cinnamon roll than a jelly roll, but so beit. Stand it with the seed end up in the corner of a black, plastic box, and put a half an inch of water in the bottom to keep the roll moist. Holding the seeds up like this, the roots grow down, fairly straight. When ready to use the roots, unroll and the white roots are easy to assess on the brown towel. Also the stiffness of the towel keeps the roots from burrowing into the germination paper and thus vanishing.

With any luck, the roots will be a cm or two long on Monday and I can transplant them onto a square plate and get the focus and lighting all juicy. And after that, let the root experiments roll.