Table 1.

Factorial ANOVA for the volumes (%) of medulla, inner cortex and internal lumen in the thallus of C. stellaris

	Source of variation	d.f.	Sum of squares	Mean squares	F	P
Medulla	N treatment	2	0·02	0·01	2·26	0·118
	P treatment	1	0·04	0·04	8·24	0·007
	N × P	2	0·02	0·00	1·75	0·189
	Residuals	36	0·16
Inner cortex	N treatment	2	0·00	0·00	0·36	0·699
	P treatment	1	0·00	0·00	0·79	0·380
	N × P	2	0·00	0·00	0·25	0·783
	Residuals	36	0·07	0·00
Internal lumen	N treatment	2	0·01	0·00	1·97	0·154
	P treatment	1	0·06	0·06	18·57	<0·001
	N × P	2	0·02	0·00	3·13	0·056
	Residuals	36	0·11	0·00