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the ccelom, on the ventral side of the abdomen, in the 

 region of the second, third, fourth," fifth, sixth, and seventh 

 abdominal segments. 



The shape of the genital-cells in always more or less 

 oval (fig. 4), the nucleus resembling the cell in shape. 

 The genital cells are surrounded by a thin cell-wall; the 

 plasma stains red with eosin, and is granular in appea- 

 rance. It often contains as many as three vacuoles; one 

 at all events seems never to be wanting. 



The nucleus stains only a little darker than the plasma, 

 and is little influenced by hematoxylin. The chromato- 

 phores are distinctly visible in the shape of bands of 

 darker-stained substance. The nucleus also seems to be 

 separated from the cell-plasm by a thin membrane. 



The micro-nucleus is very conspicuous; it is always 

 perfectly round, and stains very deeply with ha3motoxylin. 

 It is almost always surrounded by a clear space containing 

 little stainable matter. It is always found inside the nucleus. 

 The average measurements of the genital cells are : 

 — Length of cell '07 mm., breadth of cell *03 mm., 

 length of nucleus '03 mm., breadth of nucleus '02 mm., 

 diameter of micro-nucleus '004 mm. 



11. The Muscles. — The two chief systems of 

 muscles have already been referred to under the heading 

 Ccelom. They are at this stage very well developed, and 

 are composed of smooth fibres only. 



Pereyaslawzewa (38) declares that the muscles of the 

 cephalothorax are all striated, those of the abdomen being 

 all smooth. It is hard to understand why this should be 

 the case, and I think that the statement requires further 

 confirmation, especially as all the muscles are derived 

 from the same segmental sources, both in cephalothorax 

 and abdomen. 



12. The Yolk. — It is now only necessary to state 

 that pari passu with the development of the central 

 nervous system and with the contraction and withdrawal 

 of the ventral ganglion-cord into the cephalothorax, the 

 chief bulk of the yolk has been forced back in the ab- 

 domen, as is the case with all Arachnids. 



