Table 1

The number of sections not covered by the coverslip that were covered by balsam, and the number of levels where material was obscured by balsam; if two levels were mounted the level was only considered to be obscured if both sections were obscured

	Number of sections
	0	1	2	3	4	5	6	7	8	9	10	p Value
Number of sections not protected by the coverslip
Two sections/level	158	15	9	4	2	1	1
One section/level	42	1	0	0	0	0	0					0.016
Number of sections covered by mountant
Two sections/level	75	31	41	24	14	5	4	1	1	3	1
One section/level	36	3	1	1	0	1	1	0	0	0	0	<0.0001
Number of sections obscured by mountant
Two sections/level	93	33	41	15	12	3	2	0	1
One section/level	41	2	0	0	0	0	0	0	0			<0.0001
Number of levels with both sections obscured by mountant
Two sections/level	158	36	3	2	1	0	0
One section/level	43	0	0	0	0	0	0					<0.001