12 Coccus affecting the Orange. 



stigmata, because from these radiate a number of exceedingly 

 fine lines towards the circumference of the body (of the 

 insect), arching and uniting much in the manner of the 

 trachese or respiratory tubes of insects ; but these tube-like 

 lines I am unable to make out as being constructed on the 

 same plan as those of higher insects, which consist of a spiral 

 fibre closely rolled up inside them, in order to keep them 

 from collapsing ; but analogy would lead us to infer that 

 they are so constructed. And here we have a difficult point 

 for the microscopist to solve, requiring good management, 

 and a very powerful instrument, in order to verify the fact. 

 By manipulation of different kinds it will be found that 

 there exists a central body, which is itself surrounded by a 

 number of perhaps thirty or more vesicles, contained in 

 a part extended nearly all round the body, except the notch. 

 These vesicles appear to contain a multitude of minute oily 

 dots, and are the ova or eggs of the insect, which may, by 

 careful observation, carried on during the whole of the 

 season, lead to a further acquaintance with facts of interest 

 in physiology. In some, which have become more advanced, 

 I have recognised the central mouth -like part even in this 

 the egg condition. Each scale, when removed from the 

 orange surface, leaves behind a small white pit or cavity, 

 in which the insect fed upon the juices of the plant. This 

 pit is lined with a white substance, which appears to have 

 been excreted from the animal, and is not due to any abrasion 

 of the cuticle of the orange. When we lift up the scale, to 

 remove it, it will be often found that this depression contains 

 in its centre two or three fine brown hairs, of extreme 

 tenuity : these are the bristles or setce to which I have 

 alluded, and by which the insect is evidently anchored 

 securely to the orange, and by which, I believe, it derives 

 its nourishment. It also accounts for the frequent absence 

 of these organs in the specimens when examined ; and if 

 this is really the mouth, may also explain the difference of 

 opinion expressed relative to their number in some species ; 

 and, therefore, should be a point for observation by any who 

 investigate the structure of the species of Coccus. The best 

 specimens will, I think, be found in those oranges which are 

 of a light yellow colour, and in which the scales are not over- 

 crowded, as also in the more recently imported fruit. 



There is another fact worth remarking, and one which I 

 have noticed in the case of other Cocci infesting other plants, 

 that these insects are always accompanied by mildew, or 



