The preliminary test results to explain the mysterious epidemic that caused violent vomiting in more than 225 Harvard students last week have been delayed.

The results of some tests of environmental factors and a survey of 340 affected and non-affected students were expected yesterday, but University spokesperson Joe Wrinn yesterday said he now hopes for tomorrow.

Wrinn said investigators will pass out a second round survey today to probe the symptoms of the sickness in more detail, and they will release more results when that survey is complete.

The investigation will continue until all the information is compiled in a computer database to find all possible connections between the illness and the environment, according to a University press release.

But it is likely that the epidemic's cause will remain unknown, Wrinn said.

Yesterday marked the end of the first attempt to find a link between the environment--experts tested for contamination in food, air and water--and the results of biological tests of victims of the illness.

The environmental tests, which have discounted such possible causes as salmonella, shigella, campylobacter and yersinia strains of bacteria, were administered by the Centers for Disease Control and Prevention in Atlanta, S.C., and the Food and Drug Administration in Washington, D.C.

Medical experts will continue to search for less obvious links.

They must wait for the results of secondary surveys passed out to epidemic victims today, and further tests and the analysis of students who continue to suffer symptoms.

By 5 o'clock yesterday, no new students had entered Stillman Infirmary with symptoms similar to those of last Tuesday night. This figure brings the number of students reporting such symptoms in the past two days down to the number the infirmary receives on a normal day, Wrinn said.

Tests of antibodies in victims' blood will take a month to analyze. The first environmental samples will be cultured again to look for toxins.

The investigators continue to examine stool and vomit by electron microscopy for viruses. One of the investigating doctors from the Center for Disease Control is an expert in virology.

The epidemic first struck the Harvard campus last Tuesday night, when hundreds of students reported symptoms of vomiting, nausea, diarrhea and dehydration to the University Health Services.