Thick and thin blood smears are used to determine whether you have malaria. If one test is negative and no parasites are found, blood smears are repeated every 12 hours for a few days to confirm that there is no malaria infection.
Blood smears are taken most frequently from a finger prick. Thick and thin blood smears are used to determine the percentage of red blood cells infected (parasite density) and the type of parasites present.
* A thick blood [/COLOR] smear is a drop of blood on a glass slide. Thick blood smears are most useful for detecting the presence of parasites because they allow a larger sample of blood to be examined (often there are few parasites in the blood at the time the test is done).
* A thin blood [/COLOR] smear is a drop of blood that has been spread across a large area of the slide. Thin blood smears are most useful in determining what species of malaria is causing the infection.
re: thinning the blood
...paint or ink or orange juice: thin blood is more liquid (watery) than thick
blood. Having thin blood--not too thin, of course--is good because it lowers...
Thinned Blood
When you first arrive at the Santa Monica beach, talk with the guy named E. (the strange man with no shirt on). He'll tell you about problems he and his buddies have had ever since they were brought into vampirism[/COLOR]. Apparently, they're not full vampires, but instead called "Thin Bloods[/COLOR]", due to the fact that they still retain many human characteristics. E. doesn't understand what a "Thin Blood" is and wants you to investigate it for him....
I'm sorry, I forgot pasting the source before. The full sentence in the Novel (in fact it is in the Introduction part) is as following:
'Whilst Angel Clare is thinblooded,'fastidious' and racked with shallow doubts in an equally conventional, though more high-minded way.'
The third explanation of Adelyn may be more appropriate.