They reached the brain, but were stopped at the entrance.
What blocked them was a gigantic wall. It looked like the Great Wall, but it wasn't made of bricks. It was formed from a massive net.
[Blood-Brain Barrier: Refers to the barrier between blood plasma and brain cells formed by the walls of brain capillaries and Glial Cells, as well as the barrier between blood plasma and cerebrospinal fluid formed by the choroid plexus. These barriers can prevent certain substances, most of them harmful, from entering brain tissue through the blood.]
At regular intervals, there was a watchtower atop the net-like Great Wall, with guards standing watch on it.
The guards wore military-green uniforms and carried long rifles, eyeing every substance that tried to enter the brain.
Tang Yuan looked up and narrowed his eyes.
[Glial Cells: Also known as neuroglia, these are all the cells widely distributed throughout the central nervous system other than neurons. Their number in the central nervous system is approximately ten times that of neurons. They support and nourish neurons, and also absorb and regulate certain active substances.]
Through the transparent, net-like Great Wall, Tang Yuan could see many buildings that looked like libraries. Another kind of tree-like structure connected all those buildings.
Many people in green clothing lived in those libraries. They looked like scholars or researchers.
"Who goes there? The brain is a restricted area. No cells are allowed to visit." The guard atop the watchtower barked at them.
Tang Yuan rubbed his chin. This is troublesome. He had almost forgotten about the Blood-Brain Barrier. Most highly hydrophilic substances and macromolecules couldn't pass through it.
The exchange of substances here also relied on a carrier protein. Under normal circumstances, there was absolutely no way he could get inside.
"What do we do? Should we try forcing our way in?" Qi Zhi charged toward the net-like Great Wall as soon as she finished speaking. The giant net blocked her and sent her bouncing back.
Wang Tianyi looked at Qi Zhi. "You're too big. There's no way you'll get through, and—"
The guards atop the watchtower had already noticed their intentions. They raised their rifles and aimed at them.
"Misunderstanding, misunderstanding! We only wanted to see whether the wall was sturdy!" Wang Tianyi said with a fawning grin.
"Neutrophils, Macrophages, B cells, and Killer T Cells, this is no place for you. If you don't want to die, leave at once."
"Looks like we can only retreat." Qi Xiu turned around to leave, but Qi Zhi pulled him back.
"Look at him. He hasn't moved yet." Qi Zhi pointed at Tang Yuan.
Tang Yuan stood there, as though waiting for something.
"He hasn't given up, so he must have a way."
Tang Yuan indeed had not given up. He waved both hands at the people inside, signaling for them to come over.
After all, the cells had already been anthropomorphized, so this sort of interaction should still be possible, right?
Someone inside had noticed Tang Yuan. He walked straight out of one of the libraries and arrived before the wall of net-like structures.
"Hey, what's up?" the scholar asked, tilting his head. He was puzzled. Normally, no one came here. Their libraries were connected to almost the entire neural information network, so as long as they stayed in the brain, they could know everything that happened.
"You know this world is on the brink of destruction, right?" Tang Yuan asked.
The scholar nodded. He knew the situation all too well, but since he wasn't on the front lines, he couldn't personally experience how brutal it was.
As long as those viruses and bacteria didn't invade the brain, there was still room to turn things around.
"The invading virus is extremely powerful, and it mutates incredibly fast. Soon, we won't be able to distinguish between them."
"Yes, you're right. But all we can do is keep analyzing new virus strains and quickly formulate countermeasures."
"That's too passive." Tang Yuan sighed. "We need to anticipate their next moves to have any chance of winning this war. And I've got some leads."
"Yes, we welcome anyone with ideas, but I'm sorry—you still can't come in."
"I'm not trying to go inside," Tang Yuan replied. "If I have enough information, I can figure out what disease this is. So I hope you can do me a favor."
"What favor?"
"I want you to show me all the memories related to this disease."
"I'm sorry, but you don't have permission to see this." The scholar flatly refused and was about to go back.
"Wait, don't leave so soon." Qi Zhi stood there, smiling leisurely. "We're all doing this for world peace. Since he has a way to identify this disease, why not let him try first?"
Qi Zhi spoke in the gentle, low voice of a mature woman. It immediately reminded Tang Yuan of the female hosts on late-night radio, speaking in that same enchanting tone.
"But that isn't in accordance with the rules," the scholar stammered. The woman opposite him was simply too forceful, and he had no way to reject her outright.
"Just say you want to look at it yourself, then bring it over and read it through the net-like Great Wall. It's all the same. Rules are dead, and they were created for the sake of talent." Tang Yuan spoke up. The other party was wavering, which meant there was a chance.
"But..." The scholar still wasn't completely convinced. Even with Qi Zhi constantly urging him, it was no use.
"I'm sorry to trouble you. Just this once. Asking you to bring everything would be too much, so bring whichever records you can. As long as they're from the most recent period."
"Fine," the other party answered readily.
Qi Zhi had intended to keep persuading him, but she hadn't expected him to agree so readily.
What she didn't know was that, where she couldn't see, Tang Yuan had secretly grabbed the hat of the Blue Virus and waved it at the scholar.
"If you won't let me see them, I'll just find something else that can get inside and give it a try?"
The scholar's expression changed at once. "You... you wouldn't dare..."
"Oh? Let's see whether I dare." As he spoke, Tang Yuan extended the hand holding the blue hat toward the net-like structure. "At this size, it'll be easy to get inside."
This man wore a smile at the corner of his mouth, and his eyes were gentle. Yet the scholar felt his whole body go numb. He believed that this mild-mannered man was capable of anything.
So what if he was the world's Neutrophil? If he wanted to release the virus, then nothing else mattered.
[When necessary, gentle negotiation was also a way to make the other party submit.]
[Note: Gentle negotiation combined with an appropriate threat was astonishingly effective.]
The scholar went back to retrieve the records. Before long, he returned, sat directly on the ground, and looked at Tang Yuan outside the net-like wall.
"Read."
"...Sex: Female; Volunteer No. 001."
"Declaration: I volunteered to participate as a test subject. From this point onward, I voluntarily accept all consequences, whatever may happen."
"After being injected with the virus, I began coughing and sneezing. This should be a kind of inflammation-like reaction produced when the body is stimulated. They told me not to worry at all. As long as I made it through this period, I would become the first evolved person."
"But the situation seemed to be getting worse and worse. Still, I hadn't given up hope. I kept persevering without losing my sanity. I would definitely... become... the person who changed history..."
The scholar raised his head and shrugged. "This is the only relevant record. It's a medical record or diary from 'our' memories."
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