FILARIA BANCROFTI 393 



Mikrofilariae Mikrofilariae 



Lungs 134,821' Spleen 1,666 



Liver 4,884 Brain 3*833 



Kidneys 15.253 Glands o 



jGlomeruli 8,008 Marrow o 



(Parenchyma 7,245 Blood 3,ooo 



The following data of Rodenwaldt refer to the larvae of Filaria 

 iminitis in the dog. They are commoner in organs than in vessels, 

 and especially in the capillaries of the organs, but in the lungs they 

 appear to be equally distributed in capillaries, arteries and veins. 



The length of life of larvae is unknown, but they appear to be 

 destroyed in the kidneys, as dead calcified specimens are fairly 

 numerous in the capillaries of the vasa recta of the medullary 

 substance. 



Kidneys : mainly in the glomerular capillaries and those of the 

 vasa recta. 



Liver : in the capillaries of the portal system, especially in those 

 between the interlobular and the central intralobular veins. 



Periodicity of Larvce? Roughly speaking, the larvae of Filaria 

 bancrofti are found in the peripheral blood only during the night, 

 disappearing (but not entirely) during the daytime. Their periodicity 

 and that of Loa loa larvae is shown by the table on p. 394, based on 

 that of Smith and Rivas (Amer. Journ. Trop. Dis. and Prev. Med., 

 1914, vol. iii, p. 361). 



It was discovered by Mackenzie that this periodicity could be 

 reversed by making the patient sleep during the daytime, showing 

 that the phenomenon was in some way dependent on sleep or its 

 attendant phenomena. Rodenwaldt gives the following explanation 

 of the phenomenon of periodicity : 



Mikrofilariae come to rest in capillaries. After passing up the 

 thoracic duct they would reach the capillaries of the lungs by the 

 superior vena cava. Here they occur in immense numbers. In the 

 case of Loa loa larvae (which have a diurnal periodicity) some of 

 these are forced out by the increased force and rapidity of the 

 pulmonary circulation during the day, but are able to rest (owing 

 to their sticky sheath ?) in the peripheral capillaries on their way to 

 the capillaries of the organs. During the night the force of the 

 current through the lungs is relaxed and consequently they are able 



1 These figures refer to I c.c. of each organ, and were estimated by cutting sections of 

 definite thickness (30 p to 40 p.] and counting the filariae in a definite area of section, e.g., 

 | cm. 2 The organs before removal from the body have their vessels tied, and are then fixed in 

 hot alcohol. 



2 For determining periodicity measured quantities of blood, e.g, 20 mm. 3 , should be used. 

 A thick film is made of the whole quantity. The numbers present in this quantity may vary 

 from three or four to 300 or 400. 



