50 



LIFE-HISTOKY OF PARASITES. 



The Nematode Haematozoa have lately attracted considerable 

 attention by their discovery in man (Fig. 31), under circumstances 



\B 



FIG. 31. Filar M sanrjuinis Jiomlni (after Lewig). 



where they must have a considerable pathological signification. The 

 Nematode appears to be very widely distributed in the tropics of the 

 new x as well as the old world. The first discoverer of this human 

 Hsematozoon was Lewis of Calcutta, 2 and he regarded it at first as an 

 adult parasite (Filaria sanguinis) ; but subsequently considered it to 

 be the young form of a Filaria-like worm, 3 which, in the sexual state 

 (as F. Bancrofti, Cobb.), is found viviparous in the subcutaneous 

 connective tissue, more especially of the scrotum. 



[The embryos of this worm probably reach the blood through 

 the lymphatic system. According to Hanson's interesting dis- 

 covery they were usually found in blood only at night, and ap- 

 peared to be entirely wanting during the day. At midnight the 

 number of these embryos in the blood attained its maximum. 4 

 Such at least is the case when the patient preserves the usual order 

 of life, but the reverse happens if he sleep by day and wake by 

 night. 5 This proves satisfactorily that the periodical appearance of 



1 Since Magalhaes (0 proyresso medico, Rio de Janeiro, p. 375, 1878,) has discovered 

 in blood the urinary worm of Wucherer, I cannot doubt that the Brazilian form is identical 

 with the Indian parasite. The worm has also been observed in Japan and Australia. 



2 " On a Haematozoon inhabiting Human Blood," Calcutta, 1872. Ed. 2, 1874. 



3 Centralblatt f. d. medicin. Wiss., No. 43, 1877 ; more in detail Lancet, Sept. 1877, 

 p. 453. See also Cobbold, ibid., p. 495, and Vol. II. of this work. 



* Manson, J&urn. Queckett Micr. Club, vol. iv., p. 239, 1881. 

 r> Mackenzie, Lancet, August 27, 1881. 



