Classification psittacine- en structure factors

The psittacine factor can be classified in an easy way in the classificationcategories of Steiner . The category distribution is added to order the incomplete extension of pigments. This category is related to flavism or erythrism. The category shift is an incomplete shift from red to yellow or the other way round. The shift is easy to see or to prove by using the electron microscope, but is incomplete.

*Psittacine factors*
head category	category	subcategory	mutation factor	colour variety	inheritance
hypo lipo chromatism	a lipo chromatism	.	P-t factor	blue,white,grey	recessive
Mutation factor: P-t = Total loss. Total loss of psittacine pigment. The colour of the colour variety depends upon the other colouring elements. This can be blue, white, grey or black. Blue we find in green birds only. They have feathers with blue structure and red or yellow pigments in the cortex. Birds with feathers of the common type without feather structure have a white, grey or black colourvariety.
hypo lipo chromatism	chloro-lipo chromatism	.	P-d factor	seagreen	recessive
Mutation factor: P-d = Decrease. Decrease of the psittacine pigment production. Chloros (Greek) = pale. By this reduction red becomes rose, yellow become light yellow. There is a lot variety because of the other colouring elements. Some colour varieties are: parblue (partial blue), seagreen, turquoise, aqua, etc.
hypo lipo chromatism	schizo lipo chromatism	.	P-s factor	yellow or red	sex-linked
Mutation factor: P-s = Schizo (Latin) division. Devision of psittacine pigments. There are two types. The yellow pigment is gone, red pigment stays. (type 1) or red pigment is gone, yellow pigment stays (type 2) Example: the Cockatiel has an orange cheekpatch. This patch is the only featherfield that contains red pigment. When this disappears, all red pigment is gone.
hypo lipo chromatism	shift in proportion of red and yellow pigment	.	P-p factor	red, orange, yellow	recessive
Mutation factor: P-p = Proportion. The proportion between red and yellow pigment is dependent of genetic factors. Shift in proportion of red and yellow psittacine pigments is possible. We see this many times in Bourke's vareities. Some edged Bourke's have a lot of red pigment on the upper and lower back. Others are mainly yellow.
hyper lipo chromatism	flavismus	.	P-iy factor	golden pastel	recessive
Mutation factor P-iy = Increase yellow. Increase of the yellow pigment production. The golden pastel and the golden opaline-pastel Bourke's are examples of flavism. The yellow is very intensive. There is no red pigment in the back and tail.
hyper lipo chromatism	erythrismus	.	P-ir factor	red fronted	dominant
Mutation factor: P-ir = Increase red. Increase of the red pigment production An example is the red bellied and red fronted turquoisine. The red pigment formation is increased. The red opalin Bourke's shows a nearly total red plumage. Only the flights are dark brown.
hyper lipo chromatism	psittacine extension		P-e factor	red, yellow suffusion	intermediary
Mutation factor: P-e = Extension. Extension of the psittacine pigments to featherfields that does not had psittacine pigments before. Example: Bourke's parrot, the red or yellow pigment is extended to the back and tail. In the original wildtype this pigments were restricted to head, chest and belly.
*Structure factors*
head category	category	sub category	mutation factor	colour varieties	inheritance
structural alteration	formation of blue structure of the feather barb	extension of structural barbs	S-e factor	blue	recessive
Mutation factor: S-e= extension of structural feather barbes. It is a change from feathers of the common type in feathers of the structural type ( terms used by Beckmann). Colour varieties: Blue and the green Bourke's colour varieties. The Bourke's parakeet has feathers with blue structure in some area's. Feathers of the belly and chest, hindneck, upper and lower back don't have structural feathers.
structural alteration	feather barb	medulla structure	S-m factor	grey	recessive
Mutation factor: S-m = medulla structure. The typical arrangement of the cells in the medulla is disturbed by an to early and irrugular keratinization. There are no vacuoles, no arragement of cells, no spongezone. The cortex is colourless and transparant. The melanin pigment lays directly under the cortex. This takes place in the whole plumage. Colour variety: The colourvariety is dull grey and mottled.This mutation has nothing to do with the greywing
structural alteration	blue structure as a whole	keratinization	S-m factor	grey	dominant
Mutation factor: S-m =medulla. A progressive destruction of the medulla takes place. The sponge zone is very small. The arrangement of medulla cells is gone. The keratinization starts to early. because of this the vacuoles are small and numerous. The melanin grainules in the medulla are are scattered and form a dense pigment masses and not arranged in groups any longer. Colourvarieties: Green dominant grey with an olive green shade of colour in the underside and rump and white dominant grey with a greyish shade of colour the rump and the underside
structural alteration	parts of the blue structure	vacuolen	S-v factor	slate	sex-linked
Mutation factor: S-v = vacuolen. The vacuoles are the airfilled bubbels in the keratin. The vacuoles are big. Normal is that the vacuoles and the layer of melanin pigment lays under the sponge zone. An invertment took place of sponge zone and vacuoles. Each one is surrounded by a very dense layer of melanin granules.The vacuoles or the melanin layer is in some places in direct contact with the cortex. The cortex is not pigmentated. The form, format and colour of the eumelain granules is normal. This results in a dull blue colour. Colour variety: The slate colour variety is found in the budgerigar only.
structural alteration	parts of the blue structure	sponge zone	S-s factor	dark	dominant
Mutation factor: S-s sponge layer. The sponge layer is modified. The canalicular structure is composed of more irregular and most thinner channels than in the wild-type. An extremely compressed shape of the barb in comparision with the wild-type is the reason that the sponge zone is more narrow than normal.. Therefore less blue light is reflected, and more light is absorbed by the black layer of melanin. The normal depht of the sponge layer is 0,009 micron In the 1-factor variety the depht is 0,006 micron. In 2-fact. variety the depht is 0,003 micron. The narrower dimension of the barb restricts the brightness of the feather surface. The barbules are broader than normal and contribute to the darker shade of the feather also. Colour variety: Budgerigar varieties: 1- factor dark: Cobalt blue and darkgreen are 2-factor dark: Mauve and olive varieties of the Budgerigar. The refinement of the sponge layer is good documented by Steiner. Auber ads to his explanation, the narrowing of the barb and the influence of the barbules in the shade of colour.
strucrural alteration	parts of the blue structure	form of the barb	S-f factor	violet, green violet	co-dominant
Mutation factor: S-f= form of the barb. The barbs are much broader than normal. There is place for a lot of medulla cells with a sponge layer and an absorbing pigment layer around the vacuoles. The barb and sponge zone is much thicker compared with the compressed barb and the thin sponge layer of the mauve colour variety. The reflecting surface of the barb is much bigger. The barbules have less pigmentation, this gives a brighter shade of colour also. All this colouring elements result in an intensification of the colour. Colour variety: The violet colour is seen only in the blue series, not in the green series. An example is the Australian violet Budgerigar. The colour is bright bluish violet. The highes intensity of colour is found in the rump.

Structure mutations:

In principle all the structural elements can be changed by mutation. Even the form of barbs and barbules.The blue structure is a very important colour element of the parrots. Some changes concern the medulla as a whole. Other changes concern parts of the medulla structure: the sponge zone, format of the vacuoles, arrangement of the vacuoles, grouping of the melanin grains in the medulla and cortex. Shades of colour are caused by the blue structure of the barbs, and by the barbules.
Steiner did not used sub categories. This categories are based upon the research of L. Auber. Every mutation factor is indicated by a letter referred to the name of the cause. Colour names are reserved for colour varieties.
"The colours of feathers and their structural causes in varieties of the budgerigar" by Ludwig Auber, (1941) give a very detailed picture of the feather barbs and the changes by mutation.

Light absorbing medium: