igo^. Reviews, 159 



the air. and while, after the flight, the males quickly die, the females 

 become the founders of new colonies. According to M. Janet, a new 

 ant-colony is always founded by a single queen, but in some species — 

 such as Myrmica rubra and Formica riifa — the workers bring back to the 

 nest some of their own 3'oung queens which have paired at no great dis- 

 tance ; thus the community comes to contain a number of queens. M. 

 Janet kept a queen of Lasius alienus for nearly ten years. 



When the wings are shed the rupture of course takes place at the base 

 of the organ, but the exact position of the scar is not constant. "There 

 is not, as in the leaf-stalk, a special, dehiscent layer which determines 

 precisely a surface of rupture. This rupture indeed alwa5'S takes place 

 nearly at the same spot in the basal region of the wings, but it varies 

 somewhat markedly in form and position." Of a number of queens of 

 Lasius niger observed by M. Janet, only one retained her wings three days 

 after the nuptial flight. 



Attention is drawn by the author to the great size of the flight-muscles 

 in these queen-ants, filling, as they do, most of the space in the large 

 convex, thoracic skeleton. Yet these " heaviest and largest organs in the 

 queen's body are functional only once during her life, and that only for 

 some hours, in the early period of an existence that lasts normally for 

 at least twelve years." Their work over, these great muscles disappear 

 by a process of histolysis ; leucocytes and granular amoeboid cells become 

 numerous among the muscle-fibres, whose contractile substance and 

 nuclei undergo a somewhat rapid degeneration. As a result the blood 

 becomes greatly enriched by the albuminous constituents of the broken- 

 down muscles, and, in this way, the 3'oung queen is provided with a 

 supply of food, and is able to produce numerous eggs, and — through 

 pharyngeal pouches — to feed her larvae until these develop into the first 

 workers, who undertake to procure food for the colon)-. 



With the process of histolysis occurs the replacement of the muscles 

 by columns of fatty tissue, developed from gioups of cells of diverse 

 origin. Some are present before the nuptial flight, others develop 

 later between the bundles of muscle-fibres, and others again arise 

 within the muscular envelopes. It thus appears that the result is 

 analogous to a fatty degeneration, though, as we have seen, it is not truly 

 brought about by such a process, and it has a high physiological value 

 in the life of the queen ant. 



Many other points of great interest to the entomologist are discussed by 

 M. Janet. The structure of the thoracic exoskeleton is described in 

 detail, with an account of the origin of the chitinous cuticle and the 

 method of attachment of muscle-fibres to its inner surface. The memoir 

 abounds in facts and suggestions of the highest value ; the concluding 

 summary, in which comparison is drawn between the post-nuptial 

 process described and the histolysis and histogenesis that take place 

 during metamorphosis, is worth}- in particular of careful study. M. 

 Janet has added to the obligation under which he has already laid, all 

 lovers of insects and their waj's. 



G. H. C. 



