Part IV: Last episode, we learned more about crown gall; this episode
we learn a simple way to identify it.

Fari the bacteriologist had to go on vacation, but before he left, he
told me a simple way to identify crown gall using only a carrot. This
is something that any of you could do, or your children could do as
science projects.

First I cut some gall tissue as described before and teased it apart in
distilled water to release the bacteria. Then I surface-sterilized the
carrot in bleach, then used a sterile razor blade to cut it into disks.
I put the carrot pieces in Petri plates with moist filter paper on the
bottom and wet the top of each carrot slice with the
bacteria-containing water. I also took some of the colonies I isolated
last week and smeared them on top of some of the slices. I sealed the
Petri dishes to keep them moist and put them under fluorescent light.
Now we wait 2 or 3 weeks. If the bacterium is Agrobacterium, weird
tumors will arise from the carrot slices.

I inoculated the carrots on Monday; I'll be checking them every few
days to look for tumors. Wait patiently for the next episode.