An Instance of Mutation. 133 



however, a seven-segmented antenna is one of the specific 

 characters relied on by Green, a reduction had it occurred 

 then would not have passed unnoticed. Moreover, a 

 photograph of one of these earlier specimens fortunately 

 shows seven distinct segments (PI. V, fig. 1). There is 

 little doubt, therefore, that the present form is derived 

 from the typical Coccus viridis. 



The reduction is not a character acquired by the adult, 

 but appears in nymphs just hatched. This is remarkable, 

 since Green mentions as a characteristic of not only the 

 genus -Leant in in (( 'occus) but of all the genera in the family 

 that the nymphs have six-segmented antennae, and as 

 regards Lecanium {Coccus), he says, " the facts seem 

 to indicate a primitive six-jointed antenna." Maskell, 

 another authority, considers that six is the normal number 

 of segments in all Coccids. The number six in the young 

 persists in the adult, or is increased by a few more, but 

 is seldom reduced. 



Save for the inherited degeneration in the antennae, 

 the Mysore form is identical with the bug from Ceylon in 

 all microscopical details. The Ceylon specimens, obtained 

 recently, are smaller in size. It is also probable that 

 their reproductive powers are limited. Green says the 

 bug produces only about 20,* whereas in Mysore the number 

 has reached over 500. lint these are minor details which 

 do not affect the structural identity of the two forms 

 except as regards the antennae. 



Closely allied to the Ceylon form in sex. colour, and 

 antennae, specimens were obtained from one citrus plant 

 in Bangalore in May 1910. Periodical examination of 

 specimens from this plant have been made since, and so 

 far the reduction to three has not yet appeared, though 

 there seems to be a tendency for the third and fourth, 

 and fifth and sixth to coalesce. These specimens are 

 therefore the typical Coccus viridis of Green. Save for 

 this one instance a three-segmented condition of the 

 antennae appears to be universal in the South Indian form. 



It is remarkable that this seven-segmented condition 

 should be found to persist in bugs collected in 1916 in 



* I do not know where (lie author obtains his authority for this 

 statement. 1 can find no such remark in my description of the 

 species ("Coca Ceylon." iii, p. 200). On the contrary, I have 

 distinctly stated (lor. cit.) that "a constant succession of larvae is 

 produced during the life of the insect." — E. E. G. 



