MISS EMBLETON ON CERATAPHIS LATANI^. 105 



which Ceiuxtaphis latanicd lives in our liothousea are, rouglilj 

 speaking, constant, especially as regards an equable supply 

 o£ nutriment, we may conjecture that this is responsible for the 

 permanence of the aleurodiform stage. Whether the form of 

 the creature can be altered by interference with its food-supply 

 is a very interesting subject for experiment. From this point of 

 view it is of great importance that the converse experiments 

 should be made on SormapMs, or on some other migratory 

 Aphis, with a view to ascertaining whether, by supplyiag 

 successive generations with a constant supply of food under 

 equable conditions of temperature, &e., the creature could be 

 maintained for many generations, or permanently, in the 

 aleurodiform stage. 



Another factor, beyond the constant conditions oE food and 

 temperature, that may increase the tendency to the stability 

 of this transitory form, may perhaps be found in its partheno- 

 genetic reproduction ; for it has been pointed out that 

 parthenogenesis in Insecta is very couimonly concomitant with 

 the production of young that are all of one sex. 



I am well aware of the incompleteness and inadequacy of the 

 views expressed in this paper, but if this communication sliall 

 lead to experiments being instituted with this creature, then my 

 object will be attained. 



Appendix. 

 As stated on p. 95, when this paper was read, Mr. G. S. 

 Saunders made some suggestions on the subject, the most 

 important of which was that in 1879 he observed the winged 

 female. With his permission I append his remarks : — "I was 

 staying with an uncle of mine at Clifton near Bristol, who had a 

 large collection of orchids, in May 1879, when I found this insect 

 in considerable numbers on the leaves of various orchids, but 

 most commonly on Cypripediums. Knowing very little at that 

 time about insects of this nature, I took the apterous females 

 for one of the Coccidce, and I found a short account of the 

 insect in Boisduval's ' Essai sur TEntomologie Horticole.' One 

 day I was surprised to find some of the larvae had become pupae ; 

 later on I tound the females, which I then took for males, 

 and finding that Boisduval stated that the males were un- 

 known, I wrote to Signoret stating that I had found the males. 



