— 29 - 



cephalothorax; following the outer surface of the embryo 

 and reaching the cerebral ganglion it suddenly bends 

 downwards ; soon afterwards it divides into two branches, 

 which run forwards on both sides of the muscle -stomach 

 till they reach the central nervous system when, they 

 terminate abruptly. 



My embryos not being so advanced as Pereyaslaw- 

 zewa's (37), I am not in a position to state anything 

 about the other arteries and veins which she has seen ; 

 at the same time I consider her statement that the heart 

 terminates "par une artere post-abdominale" as at 

 all events not perfectly correct, since, as is hardly 

 necessary to state, the Phryniscidse have no post-abdomen, 

 either as embryos or as aduts. 



Inside the heart the blood-cells are to be seen. These 

 are large cells, staining red with eosine. 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 lie on the surface 

 of the cell, and are oblong. Each cell contains many 

 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, Pereyas- 

 lawzewa (38) having given a fuller account of them than 

 can be made out of my embryos. I have only been able 

 to find the genital germ -cells. These are the largest cells 

 in the whole embryo. They are situated in the remains of 



