STRUCTUEE AND BIOLOGY OF SCHIZONEUEA LANIGEEA. 693 
being a dirty-yellowisli colour, taking the eosin stain poorly 
and containing numerous dark coarse granules. 
Scattered throughout the body cavity are a few isolated 
roundish cells which are smaller than the pseudovitellus cells, 
and are found in the head, thorax and abdomen, but chiefly 
in the head and thorax (fig. 22, x.). They have a greyish 
granular cytoplasm and a comparatively large nucleus, and 
resemble in appearance the cells described by Dreyfus (1894, 
p. 232, fig. 13, X.), in Phylloxera. 
The Fat Body. 
When examined in normal salt solution, the fat body is seen 
to consist of yellowish-brown masses of cells, which extend 
beneath the integument and over the internal organs. The 
cells are irregular in shape, much vacuolated, and possess 
numerous olive-coloured refractive granules and shining fat- 
globules. 
As seen in sections, the fat body consists of several layers 
of cells, forming an irregular network beneath the integument 
and round the digestive tract. It is more extensively de- 
veloped in the thorax and anterior segments of the abdomen, 
and is formed from the mesoblast cells lining the integument. 
In stained sections the cells of the fat body are seen to be 
irregular in shape with a much vacuolated cytoplasm and a 
small, irregular, stellate nucleus. The nucleus is surrounded 
by a layer of granular protoplasm and a similar layer extends 
round the periphery of the cell, strands of protoplasm passing 
aci’oss the cell between the two layers. 
Bibliography. 
Ashmead, W. H. — “A Generic Synopsis of the Aphidis,” ‘ Entomo- 
logica Americana,’ vol. v, pp. 185-189 (1889). 
Balbiani, E. G. — “ Mem. sur la generation des Aphides,” ‘ Ann. des Sc. 
Nat.,’ tome xi, ser. 15, pp. 5-89 (1869). 
Blomfield, J. E. — “ Stimcture and Origin of Canker of the Apple Tree,’’ 
‘ Quart. Journ. Micr. Sci.,’ vol. 50, pp. 573-579, 1 pi. (1906). 
