They are among Harvard's most loyal citizens, associated with the University's most impressive scientific research accomplishments. They outnumber students by more than three to one, yet they almost never emerge alive from their ultra-secure quarters.

They are laboratory animals, a veritable ark-full--alligators, bats, birds, dogs, mice, rabbits, rats, guinea pigs, monkeys, lizards, sheep zebrafish. And while one might not guess it from examining the average furry inhabitant of a Harvard laboratory, these animals are at the center of a storm of conflict between University officials, government regulators and animal rights activists.

The issues are almost as numerous as the species of animals involved. animal rights activists question that ethical basis and the usefulness of experiments involving animals. Government regulators question some of Harvard's practices. University officials question the need for what they see as excessive and cumbersome government regulation.

The controversy over how laboratory mice are put to death is typical of the mixture of regulation, science and emotion that governs the treatment of Harvard's animals.

Every rodent must die when the experiment it is a part of ends. According to veterinarian Stuart E. Wiles, commissioner of laboratory animals for the City of Cambridge, there is no alternative. Once an animal is used in a study, it is considered worthless for further experimentation, Wiles says.

Killing and disposing of the animals-researchers call it "sacrificing"--is a grim task. Consider Harvard's "Faculty of arts and Sciences Guidelines for Animal Experimentation Regarding Euthanasia Procedures":

"Be certain that all animals are dead before disposal...The use of a guillotine to kill rodents is an acceptabletechnique for euthanasia, with somerestrictions...

"Decapitation should be used only when thestudy design requires this technique, because ofthe potential hazard to personnel and should beperformed by skilled personnel. Many animalspecies react adversely to the smell of blood.Animals should not be decapitated in the presenceof other animals and the investigator shall washhis/her hands between animals."

Wiles says his major accomplishment in almosttwo years as Cambridge's lab animals commissionerhas been to implement carbon dioxide asphyxiationas the method of euthanasia for small rodents.Before, Wiles says, many researchers were usinganother, less humane method of killing mice andsmall rats.

The old method, known as "cervicaldislocation," involved grasping the rodent by thehead and sharply pulling the rest of the animalaway from the head, breaking the rodent's neck.

Wiles demonstrates the method with a woodenmouse on the surface of his desk.

Although he acknowledges that cervicaldislocation is s method of euthanasia accepted bythe American veterinary Medicine Association hesays he has reservations about the practice.

Wiles argues that the problem with cervicaldislocation is that "you have to learn how to doit." And the commissioner, who also has a smallveterinary practice in the city, can't stand theidea of a mouse suffering as some rookie labtechnician struggles to snap the animal's neck.

"There are too many pitfalls in terms of doingit improperly and the discomfort that the animalsmight have to suffer," Wiles says.

Wiles says putting the animas to death in gaschambers is less painful. The gas anesthetized theanimals before suffocating them, he says.

All of the animal rights activists interviewedfor this report agreed with Wiles that carbondioxide is preferable to cervical dislocation.