DETEEMINATION OF AGE IN HONEY-BEES. 205 



16. Newton, E. T.— " On the Brain of the Cockroach," ' Quart. Journ. 



Micr. Sci.,' vol. 19, p. 340, 1879. 



17. Rennie, J., and Harvey, E. J. — "Isle of Wight Bisease in Hive 



Bees," ' Scottish Journ. Agriculture,' vol. ii, p. 2, 1919. 



18. Smallwood, W. M., and Philips, R. L. — " Nuclear Size in the Nerve- 



cells of the Bee during the Life-cycle," ' Journ. Comp. Neur.,' 

 vol. xxvii, p. 69, 1916. 



19. Snodgrass, R. E.— ' The Anatomy of the Honey-bee,' U.S. Dept. 



of Agriculture, Bureau of Ent., Tech. Series., vol. xviii, pp. 

 9-162, 1910. 



20. White, G. E.— 'Nosema Disease,' U.S. Dept. Agriculture Bull., 



1918. 



EXPLANATION OF PLATE 11, 



Illustrating Mrs. Helen L. M. Pixell-Goodrich's paper on " Tlie 

 Determination of Age in Honey-bees. 



[The figures were drawn with the aid of a camera lucida at an 

 approximate magnification of 2000 unless otherwise stated.] 



Ant. Antennal nerve pi'oceeding from antennal lobe x)f brain, c. Com- 

 missures. E. Compound eye. e. Simple eyes. Idb. Labial nerve, max. 

 Maxillary nerve, md. Mandibular nerve, n.e. Ventral nerve-cord. ass. 

 CBosphagus. as. jrL (Esophageal glands, phar. Pharynx, s.g. Sub-oeso- 

 phageal ganglion. 



Fig. 1. — Front view of the whole bi-ain after removal of the pharyngeal 

 glands. X 20. 



Pig. 2. — Right postero-lateral view of brain showing alimentary canal 

 with oesophageal glands, x 23. 



Pig. 3. —The right half of a section through the lower part of sub- 

 oesophageal ganglion of a young bee immediately after hatching, showing 

 the central mass of ganglion-cells between the fibres going to the man- 

 dibular, maxillary and labial nerves. Orth's alcoholic carmine and picro- 

 nigrosin. X 400. 



Pig. 4. — A corresponding half section through the same ganglion of a 

 bee five or six months old after hibernation, showing the necrotic condi- 

 tion of the cells. Iron-hsematoxylin and orange Gr. X 400. 



Fig. 5. — A large cell from the suboesophageal ganglion of an imago 

 immediately before hatching, showing its general plump appearance 



