Quantity Item Bausch & desired Lomb Spencer 1 Microscope without oculars, objectives or other a FF 44 1 Abbe condenser with two iris diaphragms (lower and upper) 1740 300 1 Double nosepiece 1844 450 1 16 mm. achromatic objective 1021 108 1 4 mm. achromatic objective with working distance of 0.6 mm. 1029 116 1 8 mm. achromatic objective with working distance of 1.6 mm. 1027 112 1 10X Huyghenian ocular 1104 142 1 Mechanical stage 2116 485 1 Substage lamp with Daylite glass 1774 385-B 1 Blood counting chamber (Haemacytometer with ruling of Thoma, Neubauer, Jappert, Brewer or Turk) 3550 1472 6 Cover glasses for same, 20×21 mm., 0.4 thick 3595 1460 1 Howard’s mold counting chamber (with ¾ inch inner disk) for same 3566 Special 6 Cover glasses for same 33 mm. square, 0.6 mm. thick 3598 Special 2 Cases for counting chambers 3580 1505 All analysts undertaking the Howard method should secure copies of the two bulletins of the United States Department of Agriculture written by Mr. B. J. Howard—Bulletin 569 on Sanitary Control of Tomato Canning Factories and Bulletin 581, Microscopic Studies on Tomato Products. These bulletins may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C., on payment of five cents each in coin. The details of the method as given below are reprinted from the Methods of Analysis of the Official Agricultural Chemists as amended in 1921. Apparatus (_a_) _Compound microscope_.—Equipped with apochromatic objectives and compensating oculars, giving magnifications of approximately 90, 180, and 500 diameters. These magnifications can be obtained by the use of 16 and 8 mm. Zeiss apochromatic objectives with X6 and X18 Zeiss compensating oculars, or their equivalents, such as the Spencer 16 and 8 mm. apochromatic objectives[5] with Spencer X10 and X20 compensating oculars, the draw-tube of the microscope being adjusted as directed below. (_b_) Thoma-Zeiss blood counting cell.[2] (_c_) Howard mold counting cell.—Constructed like a blood-counting cell but with the inner disk (which need not be ruled) about 19 mm. in diameter.[6]