No. 491] NOTES AND LITERATURE 



729 



which leads to a wearing out of the tissues. Thus the so-called amito- 

 sis is not concerned with cell-increase but leads to increase in surface 

 area of the nucleus, the center of cell-activity. 



The origin of the adipose tissue of the adult fly. — In most insects the 

 larval adipose tissue persists in the imago, presenting at most slight 

 modifications. In the higher Diptera, however, and especially in the 

 Muscidae, it has been found that the larval fat-tissue disappears com- 

 pletely and is replaced in the adult by a new tissue. This Berlese 

 thought to be derived from the nuclei of larval muscles, while Henneguy 

 regarded it as made up of metamorphosed leucocytes. 



Perez,^ '07, describes a condition much more in harmony with what 

 is known concerning the origin of other adult organs and tissues. 

 According to this investigator the fatty tissue of the adult originates 

 from subhypodermal groups of small, compact, mesenchymatous cells 

 which, like all young cells, stain readily in haematoxylin. These 

 groups are thus the homologues of the imaginal disks. 



The influence of nutrition on reproduction in a spider. — Lecaillon,^ 

 '07, finds that the conditions of nutrition strikingly influence egg pro- 

 duction in a common spider, Agelena lahyrinthica. Ordinarily this 

 species constructs a single cocoon, containing from 50-100 eggs. 

 Occasionally double cocoons are to be found, one capsule containing 

 a much smaller number of eggs. By overfeeding, I^caillon obtained 

 from one female five cocoons in as many weeks. Four of these con- 

 tained respectively 78, 38, 14, and 5 eggs while the fifth coco(mi was 

 small, irregular and empty. 



W. A. lllLEY. 



Notes. — The so-called double heart of the mollusk Area has been 

 made the subject of special investigation by A. Theiler {Jena. Zeitschr. 

 f. Naturwiss., Bd. 42, pp. 115-142, Taf. 9-10). The author points 

 out that it is only proper to speak of a double heart where each ventricle 

 has a separate aorta and acts independently of its fellow. Such a 

 condition occurs in Area noae, A. barbata, A. tetragona, and A. lactea. 

 In A, lactea, however, there is a common pericardium for both ventricles 



» Perez, Ch. Ori^ne du tissu a.lipeux iinaginnl choz los ^TusnMcs. C R 

 Soc. Biol. 1907. Ixiii, pp. 137 1.39. 



^Lecaillon, A. Influence de hi mitrifion siir la reproduction d'Agelena 

 lahyrinthica CI. C. R. Soc. Biol. 1907, Ixii, pp. 334-337. 



