550 
The Ohio Naturalist. 
[Vol. XV, No. 8. 
TABLE III. 
Number of 
tracheid 
Number of 
pits 
Average Diameter 
in microns 
Average Diameter 
squared 
1-4 
7 
2.6 
6.8 
5-8 
12 
3. 
9. 
9-12 
13 
3. 
9. 
13-16 
11 
3.1 
9.6 
17-20 
12 
3.1 
9.6 
21-24 
12 
3.5 
12.3 
25-28 
12 
4. 
16. 
29-32 
12 
4. 
16. 
33-36 
10 
4. 
16. 
37-40 
12 
3.3 
10.9 
41-44 
5 
3. 
9. 
45-48 
4 
3. 
9. 
49-52 
4 
2.5 
6.3 
53-56 
4 
2.5 
6.3 
57-60 
4 
2.2 
4.8 
61-64 
4 
2. 
4. 
65-68 
4 
2. 
4. 
69-72 
4 
2. 
4. 
73-76 
4 
2. 
4. 
77-80 
4 
2. 
4. 
81-83 
4 
2. 
4. 
Measurement of ray pits of Picea sitchensis, through one annual ring of 
83 tracheids. 
TABLE IV. 
Number of 
tracheid 
Number of 
pits 
Average Diameter 
in microns 
Average Diameter 
squared 
1-2 
5 
3. 
9. 
3-4 
5 
3. 
9. 
5-6 
6 
3.5 
12.5 
7-8 
7 
3.5 
12.5 
9-10 
8 
3.5 
12.5 
11-12 
7 
3.8 
14.4 
13-14 
6 
3.9 
15.2 
15-16 
5 
3.5 
12.3 
17-18 
7 
3.8 
14.4 
19-20 
5 
3.5 
12.5 
21-22 
2 
3. 
9. 
23-24 
5 
3. 
9. 
25-26 
4 
3. 
9. 
27-28 
5 
3. 
9. 
29-30 
4 
3. 
9. 
31 
2 
3. 
9. 
Measurement of ray pits of one annual ring of Picea canadensis with 31 
tracheids. 
