DAVAINEA 6l 



by improving the condition of the digestive organs, as 

 geophagy appears to be one of the methods by which in- 

 fection is acquired, and this usually results from digestive 

 disturbances. 



H. diminiita is a still smaller variety which is rare, but 

 of wide distribution, and doubtfully a different species. 

 The normal hosts are said to be rats and mice. 



DAVAINEA. 



In Davainea the testes are numerous, the mature 

 segments are much longer than they are broad, and the 

 eggs are not enclosed in the uterus, but early escape and 

 form masses large enough to be seen with the naked eye 

 in the parenchyma. The suckers are surrounded with 

 small booklets. 



FIG. 28. Nearly mature segments, Davainea madagascariensis. 

 (British Guiana.) 



Insectivorous animals such as birds are the usual hosts 

 of both Hymenolepis and Davainea, and probably in 

 both genera insects are the usual intermediate hosts. 



Davainea are rare parasites in man, but have been 

 found in Mauritius, Madagascar, Siam, the Philippines 

 and British Guiana. It is not certain if all the specimens 

 belong to the same species. They appear to cause no 

 symptoms in the recorded cases. 



The first described species in man was the Davainea 

 tnadagascariensis, about 30 cm. in length. The mature 

 segments are 2 mm. in length by 1*4 mm. in breadth. 

 The egg-masses are conspicuous, and each contains a 

 large number of eggs (fig. 28). 



