Moore. — New Species of Parasite in Trout. 87 



the single European s^tcxtSyOctomitus intestindis truttae, common 

 in the rainbow and brown trout. 



The ordinary adult form or motile trophozoite is pyriform in 

 outline, broad at the anterior end and bluntly pointed at the tail. 

 Its length varies from 6 to 12 micra and its width from 35^ to 5 

 micra. Its neuro-motor system resembles that of its close allies, 

 Hexamitus and Giardia; the two nuclei are anteriorly placed and 

 presumably connected with the six anterior flagella and with the 

 two axostyles, which sweep outward at the caudal end as the two 

 posterior flagella. Parabasals are not a constant feature. A cyto- 

 stome is not clearly marked in the adult form, though it is a distinct 

 feature of the juveniles. 



By artificial culture methods motile juvenile forms have been 

 obtained, but development by artificial means has failed to show the 

 adult form. It is assumed that further development requires en- 

 cystment conditions presented by the wall layer of the intestine. 



The mode of increase is by binary fission with a longitudinal 

 splitting and by multiple fission. In the latter case the multiplica- 

 tion of nuclei follows rapidly on encystment of the adult and struc- 

 tures are produced which strongly resemble micro and macroga- 

 metes. 



Preventive measures should follow the lines of thorough sani- 

 tation. Internal medication is impracticable and hope lies in the 

 adoption of thorough sterilization methods, which should keep 

 the disease in check. 



Octomitiasis is a disease of considerable economic importance 

 because of the limitations and restrictions it places on the output 

 of the trout hatcheries, representing large investment of capital in 

 state, federal, private and commercial hatcheries. 



The study of the disease from the standpoint of comparative 

 medicine is suggestive of beneficial results in terms of human 

 economy. 



REFERENCES. 



Alexeieff, a. 



1910. Sur les flagelles intestinaux des poissons marins. Arch. Zool. 

 Exp. et Gen., 46, i-xx, 12 figs, in text. 

 Benson, W. 



1908. Bau und Arten der Gattung Lamblia. Zeitschr. f. Hyg. u Infekt., 

 61, 109-114, 6 figs, in text. 



