On or before the first day of the third month next preceding each regular business session of the Legislature, each department, board, bureau, commission, agency, office and institution of the state shall transmit to the Department of Finance, on blanks to be furnished it, estimates of their expenditure requirements for each budget year, classified so as to distinguish between expenditures estimated for salaries, travel and per diem expenses, administration, operation and maintenance and the cost of each project involving the purchase of land or the making of a public improvement or a capital outlay of a permanent character, together with such supporting data and explanations as may be called for by the Department of Finance. In case of the failure of any department, board, bureau, commission, agency, office or institution of the state to submit such estimate within the time above specified, the Governor shall cause to be prepared such estimates for such department, board, bureau, commission, agency, officer or institution of the state as in his opinion are reasonable and proper.