Abstract: A spiro (indolino) oxazine compound of general formula (I) ##STR1## wherein R.sub.1 represents a group of the formula --NR.sub.2 R.sub.3 wherein each of R.sub.2 and R.sub.3, which may be the same or different, independently represents an alkyl group, or a carbocyclic group, preferably aryl, or a heterocyclic group, or R.sub.2 and R.sub.3 taken together with the nitrogen atom to which they are attached represent a heterocyclic ring having one or more heteroatoms and which may optionally carry at least one substituent selected from alkyl, aryl or heteroaryl groups;--X-- is selected from --O--, --S--, --Se--, --NH-- or --NR-- wherein R represents an alkyl group, andring A is a carbocyclic or heterocyclic ring which can be optionally substituted with a group of formula R.sub.8 as defined above, or may optionally have a carbocyclic or heterocyclic ring fused thereto; and wherein R.sub.4 -R.sub.8 are as defined in the specification.