352 



NATURE 



[January 12, 191 1 



•destroy those of other species which enter their nests, they 

 will sometimes receive females^ especially if fertilised, into 

 their communities, whether females of their own species 

 are living in the nest or not, and hence mixed nests of 

 two or more species may originate. Many instances are 

 quoted, both among European and American ants, and the 

 author sums up the various alternatives as follows : — 

 (i) isolated workers may dig a nest for the queen and 

 make their dwelling with her ; (ii) she may be received 

 into a nest which has lost its own queen ; (iii) she may 

 be received into a nest possessing a queen, whom she kills 

 and supersedes ; (iv) she may be received into a nest where 

 a queen lives, whom she does not injure, but who dis- 

 appears, either making her escape or being killed by the 

 workers ; (v) she may be received into a nest where the 

 former queen remains, and continues to perpetuate her 

 brood. 



Illustrations of these alternatives are then given, with 

 comments, and the author concludes that the formation of 

 new colonies depends rather on the behaviour of the 

 workers than on that of the queen. 



(5) Foundation of a New Colony hy Conquests of 

 "lymphs. — This section relates to cases in which a war- 

 like queen enters the nest of another species and drives 

 away the adult ants, establishing herself as the queen of 

 their undeveloped progeny. These cases form 

 transitions to those in which a queen is received 

 into the nest of another species where the former 

 queen still lives, and both species subsequently 

 live together in harmony and perpetuate a mixed 

 nest. 



II. Workers : Perpetuation of Colonies. 



(i) Perpetuation hy Workers without Allies. — 

 In cases where the queen founds a nest, and is 

 afterwards supported only by her own progeny, 

 the duties of the workers are generally less defined 

 than in bees. These duties fall under four cate- 

 gories : — nutrition, rearing, construction and pro- 

 tection, and warfare. 



(2) Perpetuation of a Nest with the Temporary 

 Aid of Auxiliaries. — In cases where a female has 

 fallen among a nest of a different species, or a 

 band of workers which have adopted her, and a 

 mixed nest is the result, a tendency seems to 

 persist to carry ofif nymphs of other species, which 

 is one cause of ant-slavery. 



(3) Perpetuation by Nutrition (Myrmecophily). 

 — This relates to the actual parasitism of various 

 species of ants which inhabit the nests of others 

 either as guests or (as in Solenopsis, to which we 



!have already alluded) as parasites. 



(4) Perpetuation by the Permanent Aid of 

 Auxiliaries.— This relates to ant-slavery proper, 

 where the mistresses are more or less completely 



■dependent on their slaves for their very existence. 



(5) Perpetuation in the Complete Absence of the 

 Workers of a Species. — The strangest cases of all 

 are p>erhaps those of certain species of ants which 

 are only male and female, and which live 

 parasitically in the nests of others." Sometimes 

 when such a workerless queen introduces herself 

 into a strange nest the workers kill their own 

 queen instead of the intruder, in which case the 

 colony is inevitably devoted to destruction by the 

 Impossibility of any further production of 

 workers. 



In his second paper M. Pi6ron reviews and 

 -comments on the views of Darwin, Wasmann, 

 Wheeler, Emery, and Santschi on the various 

 problems connected with ant-life. He regards 

 Formica fusca as an ancestral form of the genus 

 Formica, it being undistinguishable from F. flori 

 found in Baltic amber, and having thrown off a 

 series of closely related forms in most parts of the world. 

 This ant shows th*; primitive stage in which the new nest 

 is formed by the female only. Thence we pass on to 

 JF. rufa, of which the female can only found her nest 

 "With the aid of workers of her own or another species, 

 jand from thence to the stages of slavery and parasitism. 

 Then M. Pi^ron discusses the general problem of the 



NO. 2150, VOL. 85] 



origin of slavery and parasitism among ants, the theory 

 of progressive stages leading to these curious habits, thp 

 explanation of the different conduct of the females, the 

 problem of the rise of slavery and parasitism among 

 neuters, and the origin of aid and tolerance towards in- 

 truders of other species. His final conclusion seems to h- 

 that in proportion as evolution leads further and furtli' 

 from a primitive state, insects, like men, become more ami 

 more dependent on each other. Among ants, those with 

 the simplest and most primitive habits are the most 

 abundant, while as they become slave-holders, and later 

 on parasites, their colonies and individuals become rarer 

 and rarer. It is evident that when ultra-civilisation 

 degenerates into slavery and parasitism it is neither good 

 for man nor ant. 



TEMPERATURE CHANGES AND SOLAR 

 ACTIVITY. 

 pROF. F. H. BIGELOW {American Journal of Science, 

 vol. XXX., August, 1910, p. 115) has been discussin« 

 the variations of the mean annual temperature of the 

 United States of America and their relation to the changes 

 of solar activity as shown hy the frequency of sun-spots 

 and prominences. 



Prominences, magnetic field, suu-spots and the temperature amplitudes and excesses of 

 the United States. 



To arrive at a correct estimate of the mean tempera- 

 ture of the Slates and the departure from the mean for 

 thirty-three years, monthly maps showing the departures 

 of about 100 stations were prepared, and lines of equal 

 departures drawn. The product of the area under one sign 

 and the departure gives a " temperature volume." The 

 difference between the negative and positive " temperature 



