115 
which make the distinction safe and easy. I 
also found in our specimens all the caracters 
which he attributes to the intestinal form of 
Egvpt; this is undoubtedly identical with 
Sch. Mansoni. As shown by a recent com- 
munication, GONZALEZ MARTINEZ also 
came to this conclusion. 
The genus characters common to both 
species are the following: 
Localisation in the blood vessels and 
alimentation by blood. Existence of two 
sexes; males with canalis gynaecophorus, 
nematoid females. Eggs without lid, contai- 
ning a miracidium when voided. Penetration 
of the miracidium in a freshwater mollusk 
followed by formation of sporocysts and cer- 
cariae which emigrate spontaneously. Cerca- 
riae without pharyngeal bulb, with bifid tail 
and large glandular cells, infecting the ulti- 
mate host by boring through the skin. 
For distinguishing the two species the 
following apparently well established diffe- 
rences are sufficient : 
Haematobium. 
3 Testis showing 4—5 lobes. 
Anterior Vesicula seminalis. 
2 Ovary in the anterior half of the body. 
Ripe egg with terminal spine. 
Uterus long, with many eggs. 
Corpus vitelligenum short in the caudal 
forth. 
Coecum short. 
First stages in Physopsis. 
Mansoni. 
Testis with about 8 lobules. 
No vesicula seminalis to be seen. 
Ovary inthe posterior half of the body. 
Ripe egg with lateral spine. 
Uterus short, with one egg as a rule. 
Dto. long. extending over the last two 
thirds of body. 
Coecum long. 
First stages in species of Planorbis. 
Beside these, other differences have been 
indicated which refer to the dimensions of 
the body and the suckers, the distance be- 
tween the ends of the coecum and the body 
and the armature ofthe skin in the two sexes, 
but I consider themless certain and evident. 
The form of the testicle and the intestine 
may vary a little, but not to a degree affec- 
ting the distinction of the species. 
For the clinical diagnosis the form of 
the egg, found in the stool, and the localisa- 
tion of the symptoms are sufficient. 
In dead specimens the dimensions de- 
pend not only on the method of fixation, 
but also on anterior conditions which deter- 
mine the contraction or relaxation of the mus- 
cles. The latter influe so much on the live 
specimens, that any given dimensions have 
only a relative value. Ancient authors did 
not distinguish and the newer observers fai- 
led to compare the two species under iden- 
tical conditions. Of modern authors BRUMPT 
gives the following dimensions for Sch. hae- 
matobium: Male, length 10-15 mm., width 
not more than 1, female 15-20: 0,1-0,2 mm.; 
Pirajá for Sch. M.: male 12: 0,558 in the mid- 
dle, female 14,5-15: 0,168 mm.. My impres- 
sion is that Mansoni is altogether somewhat 
smaller than haematobium. 
The colour varies according to circums- 
tances and is not likely to be constantly dif- 
ferent in the two species, 
The Eggs of Schistosomum Mansoni. 
Characteristics of the eggs found in the 
stools. 
The evolution of Sch. Mansoni, outside 
of the human body, begins with the eggs 
voided in the stools. These deserve special 
study as they furnish the principal means of 
diagnosis. It is impossible to arrive at a 
sure diagnosis by any other means and in- 
deed the frequent occurrence of the parasite 
in South America was discovered only by 
constantly searching for the eggs of intesti- 
nal parasites. 
The Schistosomum — eggs are rather large 
but the shell is transparent and delicate. 
They are, therefore, not well seen in opaque 
preparations and may be easily squashed. 
Due to the scant production they are rare 
4 
