BLOOD-PAEASITES OF FISHES OCCURRING AT ROVIGNO. 131 



nent in parasites stained with iron-htBmatoxylin, which stain 

 they take up with great avidity. 



II. Trypanosoma sp. (cf. triglj;) in Trigla lineata. 

 (Figs. 29-31, 51, and 65.) 



In the three gurnards which were infected with Hasmo- 

 gregarina rovignensis a trypanosome was also found. 

 This parasite was always very rare, and never more than two 

 individuals could be seen in a cover-slip preparation of living 

 hlood. Neumann (15) gives only a very brief notice of 

 T. triglfB, from a single Trigla corax, and does not 

 remark u{)on the strength of the infection in this particular 

 case, but he states at the beginning of his paper that as a 

 rule trypanosomes appear to be very rare in the blood of 

 infected fish. 



Observed in the living condition, the trypanosomes per- 

 formed very active movements of contortion, but did not 

 actually displace themselves much in the blood-fluid. The 

 movements were of the wriggling and twisting kind so 

 characteristic of fish trypanosomes. The body would be 

 coiled into a spiral or S-shape and then unbent again only 

 to become twisted in the reverse sense with the greatest 

 rapidity. Occasionally the parasite would burrow into a mass 

 of corpuscles and pass through them. Particular parasites, 

 whose position was noted, were found to remain alive from 

 five to eight hours in the drawn blood or cover-slip prepara- 

 tions. Their movements had become extremely sluggish by the 

 end of this time, but no alteration inform was noticed. Only 

 in a single case was a parasite seen alive after a longer interval 

 (twenty-four hours) ; the body of the trypanosome was then 

 bent up and motionless but the flagellum waved feebly, show- 

 ing that the parasite was still alive. The parasites did not live 

 any better in preparations in which the blood had been mixed 

 with a drop of salt-citrate solution or of sea-water. In remain- 

 ing alive such a short time in drawn blood this trypanosome 



