63 
The Madagascar Tapeworm — DAVAINEA M ADAGASCARIENSIS a (Davaine, 
i86g) Blanchard, i8gi. 
[Figs. 107 to 108.] 
Specific diagnosis. — Davainea (p. 62): Strobila attains 25 to 30 cm. in length by 
1.4 mm. in breadth, and is composed of 500 to 600 segments, of which the last 100 
are gravid and form one-half of the total length 
of the worm. Head with 4 large, round suckers; 
rostellum retractile, 0.1mm. in diameter, plump, 
with 90 peculiar hooks (18 ju long) at its equator; 
the inner surface of the rostellum-pouch pro- 
vided with numerous minute points, which are 
found also on the inner surface of the suckers. 
Proximal segments broader than long; gravid 
segments become longer than broad (2 by 1.4 
mm.) and resemble apple seeds in shape; the 
distal 100 segments compose about one-half of 
the entire worm. Calcareous corpuscles present. 
Sexual development very rapid, so that segments 
3 cm. from head are in copula. Genital pores 
unilateral, near proximal corner of segment; 
genital cloaca deep. Male organs: Cirrus pouch 
bottle-shaped; ductus ejaculatorius very long 
and sinuous, provided with prostatic gland-cells; 
testicles numerous, 50 or more. Female organs: 
Receptaculum seminis unusually long and broad, 
extending to median line of segment and com- 
municating with oviduct; shell-gland included 
in the vitelloduct; uterus composed of a num- 
ber of tubes which roll up each side in a nearly 
globular ball; when uterus is tilled with eggs, 
the windings of the uterus unroll, extend 
throughout the segment, and lose their walls, 
so that the eggs now lie free in the paren- 
chyma; the eggs then become surrounded, singly 
or 2. or 3 together, by parenchymatic cells, 
forming egg-balls, of which 300 to 400 are present. 
Onchosphere (8 /.i to 15 ju) is surrounded by 
2 clear shells, the outer bearing 2 mammillate 
projections. 
Larval stage unknown; probably in some 
invertebrate. Blanchard suggests that cock- 
roaches ( Blalta orientalis) may possibly be the 
intermediate host. 
Habitat. — Adult in intestine of man, chiefly 
children. Fig. 107.— Head and anterior portion of 
rr, . , Davainea madagascariensis; the hooks 
Geographic distribution. Tropical regions haV e fallen from the specimen. x27. 
of Old and New World, possibly more common (After Blanchard, I899d, 202, fig. 1.) 
a Synonyms. — Taenia madagascariensis Davaine, 1870c; T. demerariensis Daniels, 
1895d. 
Bibliography. — For list of cases see Blanchard ,1899d. 
