11 
fertilized egg enters the uterus. These different organs vary in different genera and 
species (see keys, pp. 11, 15, 25, 48, 51, 62). 
The embryo ( onchosphere ) is provided with 6 minute hooks; it enters an interme- 
diate host and develops into a so-called larval stage (cysticercus, echinococcus, cysti- 
cercoid, plerocercoid), in which the head forms; upon being swallowed by the final 
host, the head attaches itself to the intestine and the segments form by transverse 
strobilation of the neck. 
INTESTINAL TiENIASIS. 
From a clinical point of view the most important tapeworms for 
man are at present three large forms ( Taenia saginata , T. solium , and 
D ibothriocephalus latus) and one small species ( Ilymenolejpis nano ) ; 
in fact, nearly our entire knowledge of intestinal tasniasis in man is 
based upon these four species. The other species reported for man 
are relatively of less importance, since they are less frequent. The 
following genera are reported for man: 
KEY a TO GENERA OF ADULT CESTODES FOUND IN MAN. 
(For genera thus far reported for man in the United States, follow roman type.) 
1. Head with two elongate or slit-like suckers; uterus forms a rosette; genital 
pores ventral 2 
Head with four cup-shaped suckers; uterus does not form a rosette; genital 
pores lateral (marginal) 3 
DIBOTHRIOCEPHALIDJE. 
2. Single set of genital pores and uteri present in ventro-median line; chiefly 
Old World Dibothriocephalus (p. 15) 
Double set of pores and uteri present in ventro-submedian lines; Asiatic 
Diplogonoporus (p. 21) 
TiENIIDJE. 
3. Large forms; gravid segments over one-third of an inch (9 to 35 mm.) long; 
uterus median wi ll lateral branches Trenia (p. 24) 
Smaller forms; ripe segments less than one-third of an inch (to 7 mm.) 
long 4 
4. Genital pores single; rostellum with not more than 2 rows of hooks 5 
Genital pores double; rostellum with several rows of hooks Dipylidium (p. 48) 
5. Suckers not armed; 3 testicles in each segment Hymenolepis (p. 51) 
Suckers armed with hooks; about 15 to 50 testicles in each segment Davainea (p. 62) 
CLINICAL DIAGNOSIS OF INTESTINAL T^NIASIS. 
The clinical diagnosis of intestinal tapeworms may be made by find- 
ing the segments passed from the anus, or by microscopic examination 
of the stools to find the eggs. For the microscopic examination no 
special technique is required. Take a small amount of fecal matter 
on the end of a match or toothpick (using a separate one for each 
stool), smear this in a drop of water on a slide, cover with cover slip, 
«This key is based primarily upon the species found in man, and on this account 
should not be relied upon for other species found in other animals. 
