CHAPTER 5

NOW WHAT?

Mom patted Tiny’s hurt leg and shook her head. “You’re right, Zoey. The cut is definitely infected. And the antibacterial cream isn’t working. What do you think we should do?”

“I don’t know.” Every time I looked at the horrible cut on Tiny’s leg, I felt like crying. It must hurt so much! I wished there was something I could do to fix it. “Wait! Can I go get my Thinking Goggles?”

Mom nodded and I dashed off.

I found them, put them on, adjusted them so they were just right, and headed back to Mom and Tiny. About fifteen seconds after putting on the Thinking Goggles, I figured it out. “An experiment!” I shouted.

Mom smiled.

“I need to get rid of the infection. The antibacterial cream didn’t stop the bacteria. I’ve got to find something that will.”

“Good thinking,” Mom said, and gestured for me to continue.

“But if I try something else on Tiny’s cut, I’ll have to wait a day or two to see if it’s working. That would take too long.” I paced around. “I need to find a way to grow a bunch of the bacteria on my own so I can test different things at the same time. And I also need to figure out a bunch of things that might stop bacteria.” I stopped pacing and turned to Mom. “Ummm … how do you grow bacteria? And, uhhh, are there other kinds of creams that get rid of it?”

“How about I help you grow the bacteria, and you research other things that will stop it?” Mom suggested.

I nodded. That seemed like it could work.

I called up to Tiny, “I need to set up an experiment to figure out how to help your cut. Could you maybe lie down out here? I don’t want to make you stand for that long. It’ll take a while.”

I grabbed my Thinking Goggles just before Tiny started nodding, and I managed to keep them on this time.

Mom fixed her hair and then gestured for me to follow her into the barn. “I need your help carrying a few things into the house, and then we’ll start cooking.”

“Cooking?”

Mom grinned. “You’ll see. For now, can you carry this and this?”

She handed me a tall bag of stacked clear and very flat … jars? The bag was labeled Petri Dishes. Then she handed me a bag of powder labeled Agar Powder. Finally she tucked one of her old science journals under her arm.

“Back to the house to get the rest!” she said and waved for me to follow her.

When we got into the house, I set the petri dishes and agar powder on the kitchen counter, and Mom put out the container of sugar, a big carton of beef broth, and a container of salt.

Sassafras, who’d missed most of the action by staying inside, paced at our feet and meowed loudly.

I grabbed a chair for him.

Mom flipped open her science journal and slid it toward me. I read the recipe out loud:

“This kind of seems like making yogurt.” I skimmed the list of ingredients again. “But way grosser! It’s like we’re cooking up some sugary-salty-beefy soup.”

Mom laughed. “When you make an agar mixture, you’re trying to create a place where almost all bacteria will grow. Different kinds of bacteria eat different sorts of things, so this recipe has a little of everything.”

She typed something on her laptop, then turned it toward me. The screen was filled with a bunch of photos of those flat jar things—the petri dishes.

“When we made the yogurt, you couldn’t see the bacteria, right?” Mom asked.

I shook my head. “Right, it just looked like milk.”

“Exactly. It was all mixed up, so it was impossible to see which parts were bacteria. Bacteria are really, really tiny, but when you get enough of them in one place, they make a dot like this.” She pointed to a picture on her computer of a polka-dotted petri dish. “The agar mixture will make a really strong gelatin. If you add bacteria on the surface of the cooled agar mixture, instead of mixing it in, it will grow in that one spot. And after a while, if enough of it grows, you can see the dots and know that it’s there.”

“Coooool!” I scrolled through more pictures on Mom’s computer. One had bright orange dots. “Look at that one, Sassafras! It’s the same color as you!”

Mom agreed. “But remember, some kinds of bacteria are very dangerous. After we add the bacteria from Tiny’s cut to these petri dishes, we’ll tape them shut and seal them in a ziplock bag. And no matter how pretty, shiny, smooth, or Sassafras-y the bacteria looks, you should never try to touch it or open a petri dish to get a better look.”

“I know. I promise—I won’t!”

Mom and I worked together to make the agar recipe from her journal. We heated everything up on the stove so the agar powder dissolved into the stinky soup-like mixture.

“This looks great, Zoey! Can you open all the petri dishes for me? Put one side of each dish onto that cookie sheet, but don’t touch the inside. If you do, bacteria from your hands can get in there and grow. We want to keep these clean so we only grow Tiny’s bacteria.”

I opened all the petri dishes carefully, and Mom slowly poured the hot agar mixture into the halves that were on the cookie sheet. She set a timer for thirty minutes.

“While we wait for these to get solid, can you two grab the box of gloves and the box of cotton swabs from under the bathroom sink?” Mom asked.

Sassafras chattered excitedly when we got back to the kitchen. I gave in and threw him a small handful of cotton swabs. He batted and chased them around the room while we waited.

When the timer went off, Mom moved three of the petri dishes to the kitchen table. “Before we do the real thing, I want you to practice adding the bacteria to the petri dish. It’s a little tricky. Remember how I said the cooled agar is like a thick gelatin?”

I nodded. Sassafras bonked into my leg while chasing a runaway cotton swab.

“It’s possible to poke through the surface of it. And if you do, it’ll be harder to see the bacteria. The first step is to take a cotton swab and rub it gently on Tiny’s cut. We’ll pretend the table is Tiny’s leg for now.”

I took a cotton swab and rubbed it really softly on the table.

“Perfect. Now lightly brush it across the surface of the agar in that first dish.”

I tried to, but my cotton swab got stuck in the agar. “Argh!”

“That’s OK,” said Mom. “Try again.”

By the third dish I was able to rub the cotton swab on the surface without poking through the agar.

Sassafras proudly dropped a soggy cotton swab he’d “caught” at my feet. I giggled.

Mom leaned over my shoulder. “Nice work, Zoey! Now it’s time to do the real thing.”