N.Y. R.R. Law § 238
In case any of the securities deposited in lieu of money as provided in section two hundred and twenty-five, shall in the opinion of the county treasurer or trust company with whom they may be deposited, fall below their actual value at the time of deposit, the county treasurer or trust company shall call upon such railroad corporation to substitute therefor other securities equivalent at their par or market value to the amount in lieu of which the securities for which they are to be substituted were deposited, and in case such other securities shall not be furnished, the county treasurer or trust company shall call upon such corporation to furnish as a substitute, and it shall so furnish an amount of money equal to the amount in lieu of which the securities first above referred to were deposited.
N.Y. R.R. Law § 238