Answer:
In order to find the blood type of the shipmate, Gilligan mixes a little blood of the shipmate with himself firstly and than with individual blood types to simplify the data by process of elimination.
Explanation:
There are a total of four types of blood groups which are as follows:
In order to find the blood type of the shipmate in the deserted needs of a blood transfusion, mixing of your blood with some of his blood is carred out: