Dec. 1, 1869.] 



HARDWICKE'S SCIENCE-GOSSIP. 



271 



the stem of the Ragged Robin {Lychnis Flosaiculi) ; 

 whilst a more erect, but allied hair (fig. 24/1), 

 occurs ou the calyx of the common Snapdragon 

 (Antirrhinum ma jus). Glandular hairs, with a 

 button-shaped top or apical joint (fig. 248) are 

 plentiful on the stem of the common Mudwort 

 (Scrophularia nodosa) and allied plants; in fact, 

 these glandular hairs would in themselves afford 

 material for an interesting chapter, of which good 

 examples are furnished by the natural orders Cheno- 

 podiacea and Labiate. This task I leave in the 

 hands of any one who may possess enough enthu- 

 siasm to follow my example. 



Arthur B. Cole. 



ANTS AS HOSTS. 



ONE of the most remarkable phases in the life- 

 history of Ants is the fact of their enter- 

 taining guests in their community ; that is to say 

 (in addition to the slaves which they carry off by 

 force from other nests and employ as workers), 

 there are insects, not of their own order, whom they 

 allow to share their abode without let or hindrance. 

 This subject has within the last few years been 

 carefully investigated by entomologists, and from 

 the results of their labours we gather that these 

 guests may be ranged in three groups. The first 

 group contains those insects which occupy the 

 " formicary," in common with the rightful owners, 

 in the larval condition only. Such is the handsome 

 rose chafer (Cetonia), the grub-like larva of which 

 is met with in the nest of the great Wood Ant (For- 

 mica rufa), feeding on the particles of decayed 

 wood, which the Ants have brought together, and 

 have imbedded in the cone-shaped mass which forms 

 the hill or roof of their underground home. 



In the second group are classed all those which 

 occupy the formicary in their perfect condition, but 

 which are not found there exclusively. To this 

 class belong members of the Coleopterous genus 

 Hister, and some of the Staphyline or burying- 

 beetles, all of which are voluntary denizens. But, 

 besides these, numbers of aphides or plant-lice are 

 constant occupants of the nest, who have not 

 sought its shelter of their own free will, but are 

 kept there by the Ants themselves. 



It is a well-known fact that Ants are particularly 

 partial to the sweet fluid which exudes from the 

 two tube-like orifices on the back of the aphis, and 

 not only may they often be seen on rose twigs and 

 elsewhere, where plant-lice abound, licking up the 

 coveted treasure, but they actually carry the little 

 animals into the nest and carefully tend them, with 

 the sole purpose of using them as so many insect 

 cows ! 



Among the tree-dwellers, Lasius fidiginosus and 

 L. brunneus most commonly entertain Lachnus 



longirostris, which gets its living off the trees to 

 which it is confined, piercing the young shoots 

 with a beak which is quite three times the length 

 of its own body. 



Where the nests are underground, the imprisoned 

 aphides support themselves by extracting the sap 

 from the roots of the grasses in the immediate 

 neighbourhood. 



Sometimes, instead of transporting the plant-lice 

 to their nests, they secure a colony of them in a 

 kind of earthen case, or they connect them with the 

 formicary by means of a covered way. 



In tropical lands, where the aphis does not exist, 

 its place is supplied to the ants by a near relative, 

 a certain small Cicada. 



Under the last class are included those guests 

 which never quit the formicary : there they are 

 born, there they pass through their several changes, 

 and there they die. The reader will perhaps be 

 surprised to hear that nearly three hundred species 

 of insects, mostly beetles, are known, in Europe 

 alone, to spend their days in this extraordinary man- 

 ner. Among them are members of the genus Psel- 

 aphus, and more than one hundred Staphylini. 



Two species of Ant, Lasius fidiginosus and 

 Formica rufa, seem to be specially given to hos- 

 pitality, as they harbour between them a very large 

 proportion of these strange guests ; but what pur- 

 pose the latter serve in the colony, what relation 

 they bear to their hosts, or what they do to earn 

 their living — these are still among the many mys- 

 teries which have yet to be solved.* — Taschenberg, 

 " Wirbellosen Thiere." 



VARIATIONS IN PRIMULACE^]. 



IN reading Mr. Wallace's interesting book on the 

 "Malay Archipelago," I have been reminded of 

 a variation of the common Cowslip, which recently 

 came under T my observation. In the work referred 

 to, there is a figure of the Primula impefialis, re- 

 markable as being limited in its geographical range 

 to a solitary mountain summit in the island of Java. 

 Instead of bearing a simple scape, this magnificent 

 species has an inflorescence three feet or more high, 

 consisting of several whorled clusters of Cowslip-like 

 flowers, arranged in tiers, one above another, along a 

 common rachis. A similar inflorescence belongs to 

 another Primulaceous plant, the Hottonia palustris 

 of our own ditches. That which is the normal 

 structure in these species is occasionally imitated 



[* The only ray of light yet thrown on the subject is due to 

 the German savant, Muller, who states, in regard to Clavigcr, 

 a near relative of the Pselaphus mentioned above, that the 

 Ants are wont to lick off moisture from a tuft of stiff yellow 

 hairs, which is found on the outer angle of this beetle's 

 elytra. But his observations do not extend beyond the fact 

 itself.— W. W.S.-} 



