7O FRANK R. LILLIE. 



characteristic of this egg. The hyaline band contains the small 

 basophile granules, and the distal hemisphere the large acidophile 

 granules (yolk-spheres). In sections stained in thionin and 

 orange G the hyaline band is bright blue and very finely granular ; 

 the distal hemisphere is orange, owing to the affinity of the large 

 yolk granules for this stain. But among the orange spherules are 

 some basophile granules, and with the centrifugal power noted 

 above, some orange spherules may be found in the basophile band. 

 But with a sufficiently high power a practically complete separa- 

 ration of basophile and acidophile granules may be brought 

 about. 



Attention must now be directed to a definite configuration in 

 the distal or yellow hemisphere, viz., a clear, spongy area which 

 extends into the base of the clear band, and which is surrounded 

 distally and laterally by acidophile granules. It is similar to the 

 central spongy area of the'normal control eggs with which it must 

 be identified. It contains relatively few granules, which are ar- 

 ranged in a coarse meshwork. The central end of this area is 

 occupied by an aggregation of basophile granules which are so 

 much more densely packed than those in the clear band, with 

 which the special aggregation is continuous, as to contrast strik- 

 ingly with it in sections ; particularly with low powers of the 

 microscope. The form of this aggregation is lunate or biconvex 

 in section, thick in the center and diminishing towards the ends. 



The large acidophile granules tend in a distal direction and the 

 smaller basophile granules in a central direction. If there were 

 no differences in resistance in the ground substance they would 

 pass in straight lines. But the fact is that they do not do so, and 

 this is prima facie evidence of differences in resistance of the 

 ground substance in different areas : 



The basophile cap in the central boundary of the spongy area 

 is a clear demonstration of this principle : In the first place it is 

 an aggregation of basophile granules ; this is proved by the stain- 

 ing reaction, always basic. That the stain is in the granules and 

 not in the ground substance is readily demonstrated in thin sec- 

 tions, and the granules are of the same size as the basic granules 

 of the clear band. In the second place, since such basophile 

 granules tend to move centrally, that is, towards the hyaline band, 



