11 



This genus has upwards of throe hundred species, nine- 

 tenths of which arc yelU)W and brown. 



Vanda tricolor, light yellow, spotted with red-I)rf)wn. 



Millonia cwieata, brown, tipped with pale yellow. 



MasdevaUia, PhaiKs, Coelogyne, Calanthe, Schombvrgkia, 

 Zygopetalum, Paphinia, Catai^etum, Trrchocentrmn, Den- 

 drohium, Lycaste, Houllelia, Darlingtonia, etc., have more 

 or less species of these colors, to which should be added 

 Odontoglonswin, with upwards of sixty species and varieties 

 of brown and yellow. 



If there be a law of progression in colors, as has been 

 maintained by one writer, where ought the various shades 

 of brown to be placed? Should they precede or follow 

 yellow? Might they not be formed from yellow as a base 

 by the addition of other pigments, or are they entirely inde- 

 })ehdent of it? Although the two colors are so frequently 

 associated with each other, the writer is of the opinion thai, 

 primarily, they were distinct and inde[)endent, but that 

 yellow also may be, and in fact often is, produced from 

 brown by oxidation or other chemical action. An evidence 

 of this is seen in Oiicidium longipe,^, where five of the six 

 segments of the perianth are chestnut-brown, but the lip is 

 a rich golden yellow. The lip of orchids is the most 

 changeal)lc in color, and as a rule has a different hue from 

 the other petals, and indeed is often variegated with several 

 colors. Crotons are foliage })Iants remarkable for the 

 changing colors of their leaves. If the recent leaves are 

 Hrst green, they are liable later to turn to a bright yellow 

 along the veins and in spots and patches ; with more age, 

 the yellow areas become scarlet, and at the same time, and 

 doubtless by the same pigment or chemical agency, the 

 lighter green of the lower surface of the older leaves changes 

 to a chocolate brown. What was green becomes directly 

 brown. Thus brown is formed without yellow, for no 

 yellow has been developed there. It is quite evident in 

 this example that some form of red, nn'ngling with the 



