ANTS AND THEIR GUESTS WASMANN. 467 



the Paussidse there is remarkable a progressive reduction in the num- 

 ber of antennal joints. At the highest step, in Paussus, the antennas 

 are only 2-jointed and the antennal club assumes the most diverse 

 forms/ among which the conch shape stands in the most intimate asso- 

 ciation wiih symphily. A fine example of this is offered by Paussus 

 Tiowa (fig. 20) fi'om Madagascar, which lives with Ischnomyrmex 

 Swammerdami. Within the interior of the conch-shaped antennal 

 cup there lies a great layer of glandular cells, as it is shown in the 

 accompanying section of the antennae of Paussus cucuUatus (fig. 21). 

 But also beneath the frontal pores, beneath the pronotal pits and in 

 the pygideal region there is found adipoid glandular tissue in large 

 extent, and vnih many Paussus the symphilous trichome structures 

 (reddish yellow hair tufts, etc.) are also richly developed in the most 

 diverse manner and on the most diverse parts of the body.^ In 

 spite of the high development of their exudatory organs, the Paussus, 

 as far as is at present known, are only licked by the ants, not fed 

 from their mouths; they live rather predatorily upon the ant brood. 

 The larvae of Paussus (of P. Kannegieteri) , described for the first time 

 with certainty by Boving, are likewise carnivorous, although their 

 physogastry and the glandular tissues at the tip of their abdomen 

 point surely enough to an incidental true guest relation. 



4.— MEANS OF PROCURING FOOD AMONG THE ANTS. 



The means employed by the ants to procure food are more 

 diversified and offer more analogies with human business activities 

 than we find anywhere else in the animal kmgdom. For many of 

 our native ants the principal source of food is the keeping of ''cattle," 

 that is, the occupation with plant lice and scale insects, which in part 

 they visit outside the nest and partly keep withm their nests, and 

 which they induce to give off then' saccharine excrements by strokmg 

 them with the antennae ("milking"). The honey-secreting cater- 

 pillars of some butterflies, too, particularly from the family Lycae- 

 nidae, are used similarly by native and tropical ants as ''cattle," and 

 also tropical Homoptera larvae furnish a rich contingent for this 

 purpose. Certain native ants (for example, Lasius Jlavus) even keep 

 the eggs of the plant lice within their nests during the whiter. Fur- 

 thermore, within six different genera of different parts of the globe 

 there are honey ants which feed up a worker cast into living "honey 

 pots," from whose crops, in times of drought, the colony procures 

 its food. The classical example, already described by McCook, is 

 the honey ant of the Garden of the Gods in Colorado (Myrmeco- 



• Species with lenticuliform antennal club, like P. arabicus and P. Favieri, according to Escherich's 

 observations, stand on a lower plane of symphily than P. turcicus, which has a conch-shapcd antennal club. 



• On the exudatory organs and exudatory tissues of the Paussidise see "Zur niihcren Kennlniss des echten 

 Gastverhaltnisses" (Biol. Centralbl., 1903) and "Modern biology and the theory of evolution (London, 

 1910), p. 364 II. 



