8 ANIMAL PAEASITES. 



interior of very various parenchymatous organs, perhaps to 

 undergo a change of skin there, but perhaps also to be swallowed 

 in the encysted state by other animals, in the lungs or frontal 

 sinuses of which they first attain their maturity, as Gurlt and 

 myself suppose. For instance, Linguatula denticulata, which, 

 perhaps, having immigrated mechanically into the nose of the dog 

 which devoured the rabbit or other herbivorous animal infested by 

 it, might become converted into L. tanioides. The entire cycle of 

 existence of any species is still very imperfectly known, notwith- 

 standing the endeavours of Van Beneden, who has done such 

 high service with regard to the development and systematic 

 position of these animals, and the good anatomical descrip- 

 tions of Diesing. Very recently it has also been found that 

 man harbours such Linguatula ; but if, with Leuckart we 

 regard those parasites observed in 1610 by Fulvius Angelianus 

 and Vincentius Alsarius, which were expelled from the nose of a 

 patient by sneezing, as a Linguatula, and not as the larva of a 

 Oestrus, with the exception of this case, these animals have not 

 been found free in the air-passages of the human subject, but in 

 other places, either in the encysted state, or enclosed in 

 cavities of the human body. We also know at present, both of 

 the Linguatula ferox found by Zenker, and of the Linguatula con- 

 stricta of Pruner and Bilharz, that in districts where Linguatulcs 

 occurred in the human subject, the same two species also occurred 

 in herbivorous domestic animals, or other indigenous Herbivora 

 (as, for example, the giraffe). 



1 . Linguatula constricta ?, (Pentastomum constrictum ? 

 Von Siebold = Bilharz). (Tab. VIII, figs. 1720.) 



Corpus elongatum, cylindricum, annulato-constrictum, antrorsum 

 rotundatum, apice caudali conico-obtusum, ventre planiusculum, 

 cutis non aculeata. Long. 6"' ', Latit. 1 '". Habitat in hepati 

 hominis nigritae. 



Pruner found these parasites twice in negroes, on the hinder 

 surface of the liver, on the mucous membrane of the small in- 

 testine (?), and on the mesenteric folds, in the form of white, 

 chondroma-like, transparent, circular projections ; or, in one case 

 (in which he probably had to do with a fresh immigration and fresh 



