746 SUMMARY OF CCIRRENT RESEARCHES RELATING TO 



for the movement of the two long hinder pairs of legs, has brought ahout 

 the great development of the thorax. 



Cecidia caused by Nematus caprese.* — Herr M. W Beyerinck has a 

 notice of the gall produced by Nematus caprese on Salix amygdalina. 

 The production of the gall is undoubtedly due to the matter secreted by the 

 poison-gland, which is, consequently, homologous with the poison of 

 Hymenoptera aculeata ; when the insect does not deposit an egg in the 

 wound which it makes the quantity of albuminous matter poured out by 

 the vesicle is always much less than when an egg is deposited ; by careful 

 observation it is possible to assure oneself that the size of the gall is 

 always proportioned to the size of the wound and the quantity of albuminoid 

 matter introduced. Bj an experiment in which the deposited egg was 

 punctured by a fine needle it was shown that the gall is dtie to the parent 

 and not to the egg ; but, of course, in such a case the gall remains small ; 

 neither the egg nor the larva are necessary for its production, though their 

 presence exercises a certain influence on the regularity of the development. 



The author has endeavoured to discover whether there is any persistent 

 alteration in the protnj)lasm of the plant or not. If we suppose that the 

 substance implicated in the substance of the gall is, like the protoplasm of the 

 plant, a living body able to grow indefinitely, or a substance which impresses 

 a persistent modification on the protoplasm of the plant, we ought — if we 

 Bhould succeed in pushing the development of the gall as one of its parts 

 beyond the stage at which it ordinarily stops — to find that the characters 

 of the gall remain invariably the same. If, on the other hand, the gall- 

 forming matter cannot either grow itself nor form a new protoplasm capable 

 of reproduction, we ought — under similar circumstances — to find the 

 characters of the organ, whence the gall was developed, reappear. Experi- 

 ment has shown that the second is the condition which obtains ; a normal 

 leaf modified by the gall-forming material grew into a normal leaf, and a 

 root into a root. 



The galls of Nematus are possessed of extraordinary vitality ; those 

 of iV^. caprese are found living long after the leaf is dead ; N. viminalis, 

 which is found on Salix purpurea, exhibits really remarkable properties ; 

 although abandoned by their inhabitants at the beginning of autumn and 

 being surrounded by damp mould during the winter, they not only remain 

 perfectly turgescent, but some of them are able, in the following summer, 

 to begin a new life. Galls cannot be inherited. The specific material 

 secreted by Nematus caprese — and what is true of it is probably true of 

 other forms — is an albuminoid substance which acts as an enzymatic body. 



Honeydew of Coccidse.t — Mr. W. M. Maskell describes the organ of 

 secretion of honeydew in CoccidsB. While examining a specimen of 

 CtenocMton elseocarpi Maskell, he noticed the sudden protrusion of an organ 

 from between the two dorsal abdominal lobes, and the excretion of a drop 

 of honeydew. The insect exhibits at the abdominal extremity a deepish 

 narrow cleft on the dorsal side of which are two rounded triangular pro- 

 truding lobes lying in the shallow groove formed by the sides of the cleft. 

 From beneath these lobes the insect rapidly protrudes a cylindrical organ, 

 composed of a basal thickish tube, bearing at its extremity another similar, 

 but much thinner. When this organ has been pushed out to its full extent, a 

 minute globule of the sweet fluid appears at its tip, expands rapidly, bursts, 

 and falls in fine spray on the leaf. The organ is then rapidly withdrawn. 



The author has described similar organs, without recognizing their 



♦ Arch. Neerland. Sci. Exact, et Nat,, xxL (1887) pp. 475-92. 

 t Traus. New Zealand Inst, xix. (1886) pp. 41-5 (I pi.). 



