Table 3.

Effect of time of addition of Porphyridium sp. polysacharide on NIH/3T3 cell transformation

Timing of Porphyridiumsp. addition of polysaccharide	Number of foci1
	MuSV-124	MuSV/MuLV
None	80	70
24 h before infection	0	0
2 h before infection	0	0
0 h at infection	0	0
2 h after infection	15 ± 4	6 ± 2
24 h after infection	50 ± 7	14 ± 4
48 h after infection	73 ± 6	30 ± 5
72 h after infection	75 ± 7	64 ± 6

¹Means of five cultures ± SD Foci were scored 12 days after infection. h means hours.