If at any time the number of members of a company is reduced, in the case of a public company, below seven, in the case of a private company, below two, and the company carries on business for more than six months while the number of members is so reduced, every person who is a member of the company during the time that it so carries on business after those six months and is cognizant of the fact that it is carrying on business with fewer than seven members, in the case of a public company, and two members, in the case of a private company, shall be severally liable for the payment of the whole debts of the company contracted during that time, and may be severally sued therefor.