Quantity of the Blood Injected in Cubic Centimeters.

0.03*

0.20

0.50

0.75

1.0

1.5

2.0

3.0

4.0

5.0

Remarks.

18

11

15 11

12

25* 25* 25*

* Previously treated with serum.

21*

11

22**

12* 9** g**

6

* The amount, 0.20, consisted of blood corpuscular sediment.

** The blood was taken from a leech.

Ameboid parasites of the second group, with and without cres-

6 10

4

5

30* 6* 17*

14

3**

4**

* Previously treated with serum.

** Bastianelli and Bignami reckoned only two days' incubation for these cases, in my opinion, incorrectly.

Crescents without ameboid forms

15

13

We see, therefore, that the average period of incubation is longer in the quartan than in the tertian, and in the latter greater than in the estivoautumnal type, with the exception of one case, in which blood was employed containing only crescents.

* Portion of a drop.

Bastianelli and Bignami first called attention to these proportions. From a small number of cases these writers estimated the average duration of incubation for quartan at 13, tertian 10, estivoautumnal 3 days.

Not much significance can be attributed to the amount of blood injected, since it is not the amount of blood, but the number of parasites in it, that is of importance, and we possess no means for counting these. Yet it is evident from these cases (see table) that larger quantities of blood caused a shortening in the period of incubation.