Wells uses a tone that combines the journalistic voice of a newspaper with the emotional soul-searching of a diary. We say the novel reads like something out of a newspaper because it has an eye for the facts. However, the diary aspect of Dr. Moreau comes from Prendick letting the reader in on his feelings and thoughts about certain events. Let's look at an example:
But, in the first place, I must state that there never were four men in the dingey; the number was three. Constans, who was "seen by the captain to jump into the gig" (Daily News, March 17, 1887), luckily for us, and unluckily for himself, did not reach us. (1.2)
Notice how Prendick takes the time to correct the facts of a newspaper article in his own story. He's detailing his dramatic escape from the sinking of the Lady Vain and quoting from another account of the event. At the same time? Seems kind of silly, right? No one in Titanic took the time to quote a newspaper while the ship gurgled its way into the frigid Arctic abyss. The effect suggests to the reader that Prendick keeps his facts straight, so we can trust what he has to say. It adds a quality of believability to the story.
But Prendick isn't afraid to tell us how he feels either. In the quote above, it's abundantly clear that Constans's death worked out for him. In this way, Prendick's emotions balance his factual nature. When Prendick goes all "Dear Diary," he reminds us that he's a person, allowing us to develop a stronger connection with him. If Prendick told us nothing but the facts, he'd sound like one of those Disneyland automatons in The Hall of Presidents, and, man, that would be boring.