402 M. Victor Faussek on the Anatomy and 
and sometimes larger, are found between them. At the 
periphery of the yolk, where the splanchnic layer of the 
mesoderm adjoins it, there appears (even before its division 
into the future hepatic sacs) a number of small cells with 
small round nuclei; these cells, which in all probability split 
off from the large endoderm cells, settle down upon the 
visceral layer of the mesoderm and form the epithelium of 
the mesenteron. ‘Thusit is not the endoderm cells themselves 
but their derivatives which give rise to the epithelium of the 
mid-gut (figs. 31 and 32), 
9. The coxal glands of an adult harvest-man consist of 
three divisions :—(1) the inner end is expanded in the form 
of asac, and constitutes the terminal vesicle; (2) the terminal 
vesicle narrows and passes into a very long convoluted tube, 
the tube of the coxal gland, which has long been known 
(Malpighian vessel) ; (3) the tube empties itself into a large 
thin-walled sac (urinary bladder), which opens to the exte- 
rior at the side in the cephalothorax, between the coxee of the 
third and fourth pairs of legs. The terminal vesicle of the 
coxal gland has hitherto never been described. It is situated 
in the cephalothorax as an elongated saccule, at the side of 
the ganglionic mass surrounding the cesophagus, at the base 
of the third pair of legs; at the anterior end the saccule 
bends downwards and somewhat inwards, runs a little way 
backwards, and terminates blindly near, and on the inside of, 
the external opening of the coxal gland (fig. 50, es’). In 
transverse sections we therefore see two lumina, one above 
the other (fig. 23, es”, es’) ; but on scrutinizing a series of 
sections we can easily convince ourselves that both lumina 
pass into one another anteriorly, while posteriorly the lower 
saccule (the doubled-down anterior end of the terminal 
vesicle) ends blindly and the upper one becomes narrower 
and passes into the tube (fig. 50, es’, es, cow”; fig. 34, es? ; 
fie. 35, coz”). This tube, at first excessively thin (figs. 50 
and 35, coa*), becomes gradually wider, and passes into the 
long-known convoluted tube, the ‘ Malpighian vessel” of 
Plateau, the true significance of which was first recognized 
by Loman *. The tube of the coxal gland forms a compli- 
cated coil, passes towards the dorsal side of the body, where 
it makes a loop running parallel with the heart, then returns 
* Plateau, “Sur les phénoménes de la digestion, etc. chez les Phalan- 
gides,” Bull. Acad. Belg. 1876; Rossler, “ Beitrage zur Anatomie der 
Phalangiden,” Zeitschr. f. wiss. Zool. Bd. 84, 1882; Loman, “ Altes und 
Neues uber das Nephridium (die Coxaldriise) der Arachniden,” Bijdr. tot 
de Dierkde. N. A. M. 14 Aufl, 1888. The recent paper by Sturany 
( Die Coxaldriisen der Arachnoiden,” Arch. Zool. Instit. Wien, 9 Bd., 
1891) came into my hands after my memoir was quite finished. 
