SCIENCE-GOSSIP. 



239 



crab, and always as the latter increased in size the 

 anemone kept pace with it. So it comes about 

 that without the trouble of changing residences the 

 crab is furnished with a covering to its tender 

 abdominal region, and one that is far lighter 

 and more easily carried about than the heavy 

 whelk -shells of its near relatives. At tirst these 

 smiled at brother Pagiinis dragging upon him a 

 double load, but now in later life the Pagui'iis can 

 turn the laugh the other way. The anemone is 

 soft, and might hardly, perhaps, be considered a 

 sufficient protection, but its surface is studded with 

 stings, by means of which it can drive away many 

 enemies that even the hard whelk-shell might not 

 satisfactorily keep off. The advantage to the 

 anemone. is of course obvious: in tearing up its 

 food the crab lets many fragments slip by, and 

 these are readily caught up by its partner. Again, 

 the slowly movable anemone is borne rapidly from 

 place to place not only away from external dangers, 

 but also into "fresh fields and pastures new," 

 where it can gather in abundant and varied diet. 



In conclusion, we may turn to yet another 

 instance of symbiosis in which man himself forms 

 one link. Many micro-organisms, as we know to 

 our cost, take up their habitation in the different 

 organs of our bodies and produce in them various 



diseases. J^ut micro-organisms are of many kinds, 

 and by no means all 'harmful ; some varieties reside 

 normally in the body and gain, it is true, advantages 

 for themselves, but give also advantages in return. 

 Thus the intestinal portion of our digestive system 

 is swarming with bacteria. The food that reaches 

 this portion of the alimentary canal is acted on to 

 some extent by the micro-organisms, which extract 

 from it some parts for their own use, and in doing 

 so aid in the chemical processes which collectively 

 constitute digestion. 



How far these bacteria share in the many 

 changes of our food is not yet completely under- 

 stood, but that they do take a share we fully realise, 

 and some of the changes they effect we already 

 know. The complete story of their work and the 

 checks which the body exercises on their too rapid 

 increase is still, however, a tale which the future 

 must unfold. 



Many and curious are the associations which we 

 have seen between organism and organism, but none 

 stranger than this last example, where, indeed, the 

 extremes meet, and the simplest and the highest of 

 organisms, the bacterium and man, join in the 

 common issues of life. 



Elmwood, Bickley, Kent ; 

 January, 1897. 



SCALE INSECTS. 



CocciD.E Associated with Ants. 

 By T. D. C. Cockerell. 



TT is well-known to entomologists that ants' nests 

 contain a varied and peculiar fauna, in addition 

 to the ants themselves. These messmates and 

 parasites are of many kinds, and a full list of them 

 will be found in Wasmann's " Kritisches Verzeich- 

 niss der Myrwekophilen und Termitophilen Arthro- 

 poden," published in Berlin in 1894. Although 

 the species enumerated in the work mentioned are 

 very numerous, the subject is anything but exhausted, 

 and will yield good results to the collector in any 

 country. The present paper is intended to give a 

 brief account of the Coccidae known to be associated 

 with ants, in the hope that some of your readers 

 may be interested, and perhaps search for and 

 discover some additional species. 



(i) Margarodes formicarium, Guilding, 1833. 



A very curious pearl-like yellowish creature 

 found in and about ants' nests in the West Indies. 



Roland Trimen has recorded a supposed Mar- 

 garodes from ants' and termites' nests in Cape 

 Colony. In Chile the ant Brachyinyimex gianii, 

 Emery, is associated with Margarodes vitium. 



(2) Orthezia occidentalis, Douglas, iSgi. 

 About 4 millimetres long, oval, covered with white 



secretion, which is divided into lamellae. Legs 

 and antennae comparatively large. Found in ants' 

 nests in Colorado. For the full description, with 

 figures, see Ent. Mo. Mag., iSgi, p. 245. 



(3) Spermococcus fallax, Giard, 1S93. 

 This is a peculiar species found by Giard, at 

 Wimereux, on the roots of various plants, especially 

 grasses, in the nests of ants. The adult female is 

 5 to 7 millimetres long, by 2h to 3 broad, yellowish 

 fawn, primrose, with darker lines on the back. 

 The antennae are seven-jointed, the first three the 

 longest. In June the female secretes cottony 

 matter in which the eggs are deposited. 



(4) Lecanopsis formicarum, Newstead, 1S93. 



Found by Mr. C. W. Dale, at Chesil Beach, in 

 nest of Formica nigra ; for the full description and 

 figures see Ent. Mo. Mag., 1S93, p. 206. The 

 female is dusky-yellow or reddish-yellow, with two 

 broad interrupted subdorsal stripes. Length, 5 to 

 5.\ millimetres, breadth, 2 to 2^. Antennas eight- 

 jointed. It must be confessed that there is nothing 

 in Giard's description of Sp'niiococcus fallax which 

 might not apply to this insect. It is true that the 

 antenna? are said to be seven-jointed, but the 



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