Quotations of four lines or less must be put in quotation marks and incorporated into a sentence. The punctuation depends on how the quotation is used.
Note that in each case, the quote is introduced. It does not just sit in the middle of the text, with no apparent connection to the words around it. Note also the information makes clear whose words are being quoted.
Quotations of more than four typed lines are set off from the text. Begin a new line and indent ten spaces from the left margin. Do not use quotation marks, do not indent from the right-hand margin, and do not single space. Quotations set off in this manner are usually introduced with an independent clause (a clause that can stand on its own as a sentence) followed by a colon.
Marlow's response to the station and what it represents is a strange one. He is not only critical of it; he finds that it is not real:
There was an air of plotting about that station, but nothing came of it, of course. It was as unreal as everything else - - as the philanthropic pretense of the whole concern, as their talk, as their government, as their show of work. The only real feeling was a desire to get appointed to a trading-post where ivory was to be had, so that they could earn percentages. (27)
The key element in this passage is the attention it draws to the lack of authenticity in the claims of European civilization to moral justice. All those things in the list of the "unreal" are the activities designed to create the impression of justice in the imperialist enterprise. The reality is the crass profit motive these "unrealities" are dedicated to disguising.
Note that, as in the previous examples, the passage is introduced, so that the reader knows who is being quoted. Note that the question does not stand on its own or speak for itself. A quotation of this length needs to be followed by some explanation of just what it demonstrates, what it is doing in the essay.