Here's a brief explanation of the key points of Section 319 Cr.P.C.:

Summoning additional accused: If, during the trial of a case, the court is of the opinion that any person other than the accused already on trial has committed an offense and can be tried along with the present accused, the court has the power to summon such person to appear before it as an additional accused.

Evidence on record: The court can take into consideration the evidence already on record during the trial to form an opinion about the involvement of the additional person in the commission of the offense. This evidence could be witness statements, documentary evidence, or any other relevant materials produced during the trial.

Fair opportunity: Before summoning the additional person as an accused, the court must provide them with a fair opportunity to defend themselves. This means the court may hear their side of the story and allow them to present evidence or arguments in their defense.