For 80 years the infectivity of salmonid whirling disease has eluded discovery. New findings now show that this myxosporean disease of fish is initiated by what is regarded as an actinosporean produced in a tubificid oligochaete. Experimental results provide evidence that, instead of being considered as representatives of separate classes in the phylum Myxozoa, the myxosporean and actinosporean are alternating life forms of a single organism.

An established line of fish cells has been propagated in vitro for 21 months and 48 subcultivations. Important characteristics of the cells are described.

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it can be shown that TDA potentiates depressor response to isoproterenol(2).The experiments described herein were undertaken to( examine the possibility of chemical inactivation of 5-HT by reaction with TDA. Inactivation has been demonstrated but evidence regarding mechanism is merely circumstantial. TDA does react with 5-HT in vitro and the reactioin product in large doses has no measurable effect on blood pressure. It also blocks the effects of 5-HT on blood pressure in the rabbit but this may be a consequence of binding to receptor sites and not chemical combination with 5-HT. The presence of a blue color in arterial and venous plasma samples of animals treated with 5hydroxytryptophane and TDA indicates that in zvko coupling can occur but does not exclude the possibility of concurrent binding to receptor sites.The pyretogenic response to iproniazid and 5-hydroxytryptophane combinations was not modified by TDA possibly because TDA does not penetrate into central nervous system tissue in sufficient quantity, or because amount of 5-HT produced was sufficient to override a TDA blockade.Sumnzary. The tetrazo compound, tetrazotized diorthoanisidine (TDA) reduced or abolished depressor response to 5-HT in the rabbit but did not alter the pyretogenic effects of combined treatment with iproniazirl and 5-hydroxytryptophane. The mechanism by which TDA modified blood pressure response to 5-HT is discussed.

A virus from fish with lymphocystis disease was isolated in fish cell cultures. Eleven serial transfers were made and the pathognomonic lymphocystis cells were produced in vitro in each transfer. Fish inoculated with 6th- and 9th-passage material developed the disease, and virus was reisolated front them.