SCHISTOSOMA H^MATOBIUM 273 



less than 40/4 in diameter and capillaries 8//, to 20 p. Further, the 

 maximum diameter of the male worm is i mm., that of the female 

 280 yu, and eggs in ntero 80 //, to 90 //, long by 30/4 to 40 //,. 



Lm?r tfd Portal Vein. Here worms are most easily found post 

 mortem. Often only males are found and these of the same size, 

 and if females occur only a few worms are found in copula. The 

 worms are frequently not full size and the males may contain no free 

 spermatozoa in their testes, and as regards the females some may 

 be fertilized, others not, as shown by the presence or absence of 

 spermatozoa in the seminal receptacle or uterus. In either case they 

 may contain eggs lateral-spined usually one, less often two, but 

 there may be as many as five or six. These eggs may also show 

 some abnormality, which takes the form of : (i) abnormal con- 

 tents, viz., disintegrating yolk cells with or without an ovarian cell ; 

 (2) abnormal shape but with normal contents and probably repre- 

 sented by the collapsed and empty egg-shells which are found in the 

 tissues. 



As to the interpretation of these facts, Looss believes that these 

 lateral-spined eggs are products of young females whose egg-laying 

 is not at first properly regulated. The shape that the eggs take, viz., 

 with a lateral spine, is determined by an excess of material ovarian 

 and yolk cells being present in the ootype. The shape of eggs 

 depends upon the position they have in the ootype during their 

 formation. In young females an excess of cells yolk cells especially 

 accumulates, distending not only the dorsal wall but a portion also 

 of the short duct joining the ootype to the uterus. The result of this 

 is that the axis of the ootype and egg is almost transverse to the body, 

 and the posterior funnel-shaped portion of the ootype, instead of 

 being terminal, has now a lateral or rather a ventral position, so that 

 the spine which occupies this portion, instead of being terminal, is 

 now lateral. It is noteworthy that these lateral-spined eggs are 

 thicker, owing to the excess of material present, and not uncommonly 

 have a curved anterior border, due to a projection of the anterior end 

 into the anterior opening of the ootype. 



As these eggs are being laid by females in the portal vein they are 

 carried back to the liver by the blood stream. The liver is one of 

 the commonest sites for these eggs ; also terminal-spined eggs may be 

 found here for the same reason. 



Hcemorrhoidal Veins. Mature worms, generally in copula, are 

 usually found here, though young not fully grown females may also 

 occur. The tissues of the rectal wall (or colon) show, as a rule, large 

 quantities of lateral-spined eggs, though less often only terminal- 

 spined eggs may be found. 



Vesico-prostatic Plexus. Worms in copula are found in the veins 

 18 



