Introduction:
The appropriation of goods refers to the act of selecting and setting aside specific goods to fulfill a contract of sale. It is an important concept in contract law, particularly in relation to unascertained goods. Unascertained goods are goods that have not been identified or set aside for a specific contract. In this context, it is necessary to understand the correctness of the statements regarding the appropriation of goods for unascertained goods.

Correct Statement:
The correct statement regarding the appropriation of goods for unascertained goods is that the assent must be given either before or after appropriation. This means that the agreement or consent of the parties involved in the contract must be given either before or after the goods are selected and set aside for the specific contract. The assent can be given through various means, such as verbal agreement, written contract, or conduct.

Incorrect Statement:
The incorrect statement is that either the buyer or the seller can make the appropriation. In reality, only the seller has the right to appropriate goods for unascertained goods. The buyer does not have the authority to make the appropriation. The seller is responsible for selecting and setting aside the goods to fulfill the contract. This is because the seller has control over the goods and is in a better position to determine which goods should be appropriated.

Explanation:
- Assent must be given either before or after appropriation: The correct statement is that the assent must be given either before or after appropriation. This means that the agreement or consent of the parties involved in the contract must be given either before or after the goods are selected and set aside for the specific contract. This ensures that both parties are aware of and agree to the appropriation of goods for the contract.

- Only the seller can make the appropriation: The incorrect statement is that either the buyer or the seller can make the appropriation. In reality, only the seller has the right to appropriate goods for unascertained goods. The seller is responsible for selecting and setting aside the goods to fulfill the contract. This is because the seller has control over the goods and is in a better position to determine which goods should be appropriated. The buyer does not have the authority to make the appropriation.

In conclusion, the correct statement is that the assent must be given either before or after appropriation. However, the incorrect statement is that either the buyer or the seller can make the appropriation. Only the seller has the right to appropriate goods for unascertained goods.