[jambutty]

Language is an evolving beast and what was correct in yesteryear may not be correct today.

Years ago a quotation was enclosed in double quotes. Nowadays single quotes are favoured.

What about its and it’s? “It’s mine.” Is correct because the apostrophe denotes one or more missing letters. “The dog has gone to have its dinner” is also correct. Yet Peter’s dinner would be correct.

Pseudo plurals create arguments. The plural of virus, octopus and hippopotamus has always been viruses, octopuses and hippopotamuses yet the modern version seems to be virii (sometimes written as viri), octopi and hippopotami.

Cactus, fungus, nucleus. Any more?

See AskOxford: What are the plurals of 'octopus', 'hippopotamus', 'syllabus'? for loads of infromation.