"It was the damnedest thing," said Tobias Smollett, senior research fellow at the institute. "A colleague and I had just returned from a 12-hour shift of sandbagging. We were joking about a hand-painted sign we had seen down by the river. The sign read: "You saved our buildings basement. Thank you, volunteer's !"

That was when Smollett had a sudden inspiration: The two ailments - apostrophobia and apostrophilia - might be caused by separate genes.

"I had assumed that the two conditions were mutually exclusive, that people suffered from one ailment or the other, but not both. That assumption led me to search for a single source.

"I had theorized that in the 'off' position a particular gene might create a tendency for writers to omit apostrophes when indicating possession," Smollett explained, "whereas in the "on" position that same gene might lead writers to insert apostrophes unnecessarily when forming the plurals of nouns.

"But when I saw the sign by the river - with the missing apostrophe in our buildings basement and the unnecessary apostrophe in volunteer's - I realized a second gene might be at work."

After an intensive search, Smollett located both genes.

"This finding explains why in rare cases one individual, such as the person who painted that sign, can suffer from both maladies simultaneously," he said.

According to Smollett, writers can overcome apostrophobia (an irrational fear of apostrophes) and apostrophilia (an irrational love of apostrophes), by following these simple rules:

• With a singular noun, form the possessive by adding an apostrophe and an s: not the writers first draft, but the writer's first draft.

• With a plural noun ending in s, form the possessive by adding only the apostrophe: not three employee's paychecks and two bosses's recommendations, but three employees' paychecks and two bosses' recommendations.

  (Here's a helpful tip: To place the s and the apostrophe in the correct order, first make the noun plural or singular; then add the apostrophe.)

• With compound nouns, add 's or s' to the last element: not my mothers-in-law cooking, but my mother-in-law's cooking.

• To indicate joint possession, make only the last word in a series possessive: Sally and John's report. To indicate individual possession, make each word in a series possessive: Sally's and John's reports.

• Although there are exceptions to this rule, indicate possession by inanimate objects with an of phrase: not our initiative's success, but the success of our initiative.

• With contractions and dates, use an apostrophe to indicate the omission of letters or numbers: I'll, didn't, and the class of '67.

• Although the apostrophe no longer is required to form the plural of letters and numbers such as 147 MBAs and the 1990s, use it when needed for clarity: three I's and p's and q's.

• Do not use an apostrophe simply to make a noun plural: not two mistake's, but two mistakes.

• Do not use an apostrophe with possessive pronouns: not it's, her's, their's and who's, but its, hers, theirs, and whose.

• Do not use an apostrophe in descriptive phrases: not sale's record and news' release, but sales record and news release. (In some cases, it is difficult to distinguish a descriptive phrase from a possessive phrase, as in teachers manual and driver's license.)

"Apostrophobia and apostrophilia can be debilitating," Smollett added, "but they are genetically determined tendencies not predetermined behaviors. With training and practice, these tendencies can be overcome."

When asked what writers afflicted with these ailments can do to avoid embarrassing themselves and undermining their credibility, Smollett offered this advice: "Learn the rules."

Minneapolis consultant, offering training seminars in effective business writing.
Wtite to him at P.O. Box 19114, Minneapolis, MN 55419, or send e-mail to wilbers@startibune.com. You can visit his Web page at www.wilbers.com.