WHIP WORMS 269 



been reported are F. magalhaesi, F. ozzardi, F. volvulus, F. powelli, and F. philip- 

 pinensis. A species called F. gigas is now considered to have been only the hair 

 of the leg of a fly. The embryos have usually been given such names as F. nocturna, 

 F. diurna, etc. Of course the embryos and the parent should have the same name. 

 It has been proposed to designate these embryos the same as the parent, but with 

 the use of the term Microfilaria instead of Filaria. 



The points usually noted in the description of filarial embryos are: 



1 . Presence or absence of periodicity of embryos in peripheral 

 circulation. 



2. Presence or absence of a sac sheath around the embryo. 



3. Accurate measurements. 



4. Shape and description of head and tail ends. 



5. Character of movement. 



6. Location of V spot and break in cell column in stained 

 specimens. 



KEY TO FILARIAL LARVAE. 



A . Sheath present. 



1. No periodicity. 



F. philippinensis. Tightly-fitting sheath; not flattened out beyond extremi- 

 ties. Tail is pointed and abruptly attenuated. Lashing progression move- 

 ment. 320X6.5^. 



2. Periodicity exhibited. 



a. Nocturnal periodicity. 



F. bancrofti (F. nocturna). Pointed tail; loose sheath; lashing movement. 

 300X7.5,". V spot QOjW from head; break in cells 50^ from head. 



b. Diurnal periodicity. 



F. loa (F. diurna). Pointed tail; loose sheath; 245 by 7 microns. V spot 

 60 to 70 microns from head, break in cells 40 microns from head. 



B. Absence of sheath. None of these exhibit a periodicity, being continuously present. 



1. Blunt tail F. perstans. 200X4.5^- 



2. Sharply-pointed tail: 



a. F. demarquayi. 2ioX5/*. 



b. F. ozzardi. 215X5,". 



NOTE. A filarial embryo, F. powelli, reported once. It has a sheath, nocturnal 

 periodicity, and is about i^oXs^ 1 - 



TRICHOTRACHELID^E. 



These have a long thin neck and a thicker terminal portion. The 

 oesophagus is of the single row of cells type. The anus is terminal; 

 there is only one ovary. 



Trichuris trichiura (Trichocephalus dispar). This is usually called 



