Question of the week #3

In my course syllabus, I mentioned introduction to protozoology or protozoalogy; however, on the handout given I wrote introduction to protistology.
Indicate two reasons for which I made this distinction between these two terms.
(Hint: one reason is historical and the other reason is the timeline of eukaryotic taxonomy)

I expect a response to this question on a piece of paper to be handed in by Thursday the latest (before Easter break)