Page:Tropical Diseases.djvu/754

702 of caudal papillæ in the male worm has been ascertained by Leiper. There are in all two rows of fifteen each, extremely minute, mainly arranged around the anus.

The life-span of F. bancrofti and its microfilaria have not been determined. From the fact that the microfilariæ have been found in the blood many years after the opportunity of infection has passed, it is to be concluded that both of them may live for many years. Experiments with the microfilaria of Filaria (Dirofilaria) immitis have shown that in the case of



this worm the microfilaria may live for at least three years, and in this time acquire somewhat increased dimensions, but it does not follow that the inference from these experiments is applicable to microfilaria bancrofti. I have seen the latter completely disappear from the circulation within a few hours of the death of the parent worm during an attack of lymphangitis. Nothing is known of what becomes of the microfilariæ when they are effete or die.

As shown by Wise and Bahr, the mature worm becomes cretified after its death, and may be found, sometimes in large numbers, in this condition in the lymphatic vessels and glands. (Figs. 112, 113.)