624 L. H. GOUGH. 



large cells, staining' red with eosin. They are usually 

 nearly spherical^ measuring up to '036 mm. in diameter^ and 

 seem to be surrounded by a thin membrane. The nuclei of 

 the blood-cells always He on the surface of the cell, and 

 are oblong. Each cell contains mau}^ nuclei^ of which 

 one is always remarkable as being several times larger than 

 the others; this one measures "007 mm._, and is often in a 

 state of mitosis. These cells are possibly the same as the 

 fat-cells seen by Kishenonye (23) in spiders^ but are here 

 confined to the interior of the heart. Besides these larger 

 blood-cells^ smaller ones are also to be seen in the cavity of 

 the heart. These have only one nucleus^ and are poor in 

 plasma; they resemble those found in the heart in the fourth 

 stage. There the larger, spherical blood-cells are missing. 



9. The Lungs. — It is not necessary to follow the 

 development of the lungs, as it follows the same type as 

 most other Arachnids. 



10. The Genital Organs. — I am not in a position to 

 state anything new about the genital ducts, Pereyaslawzewa 

 (38) having given a fuller account of them than can be made 

 out of my embryos. I have only been able to find tlie 

 genital germ-cells. These are the largest cells in the whole 

 embryo. They are situated in the remains of the coelom, 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 is 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 appearance. 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 hgematoxylin. The chromatophores 

 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 alwa^-s per- 



