in the Cephalothorax of the Phalangiide. 89 
district [near Bonn], in which the cells may likewise be traced 
to the neck of the comparatively large sac, possesses the 
shortest and widest canals, merely bent into simple loops. In 
Leiobunum, on the contrary, the cells occupy only the bottom 
of the sac, sometimes, however, extending a little higher up ; 
the canals are certainly shorter and less strongly twisted, but 
not less fine than in the two species first mentioned. 
In all the species named the canals appear to grow gradu- 
ally a little wider, a little before they reach the intima in 
order to open into the cavity of the sac. It is, however, quite 
uncertain from what part of the cell the canal originates. 
Notwithstanding many attempts, I could never succeed in 
discovering any mixture fitted to demonstrate the direct con- 
nexion of the canal with its cell. Nevertheless, from analogy 
with certain glands in insects, we may assume that the canal 
issues from the vacuoliform space. ‘Thus, according to Ley- 
dig’s observations, there is a similar cavity, but furnished 
with a distinct membrane, in the cells of the salivary gland 
occurring in the proboscis of some Diptera, As shown in 
Leydig’s excellent figures, we here see the excretory tubule 
decidedly originating from this vesicle*. 
With regard to the secretion of the glandular sacs, I must 
confine myself to a few statements, and these, indeed, not of a 
kind to lead to any certain conclusion as to its exact nature 
and its employment during life. In the sacs of some indivi- 
duals of Phalangium and Leiobunum I detected very small 
erystalline deposits, which had a straw-yellow colour by trans- 
mitted light, and seemed to resemble quadratic or rhombic 
tables. esciest them there was in some cases a larger and 
definitely developed crystal, apparently an octahedron with 
flat truncated ends. In another example of Levobunum, on 
the contrary, the sac was distended by a milk-white fluid, 
which, under the microscope, proved to consist of numerous, 
small, colourless-oil-drops. 
To refer to the observations of preceding naturalists with 
relation to this subject, it may be mentioned, in conclusion, 
that Treviranus, misled by the rounded form of the sacs, and 
still more by their dark-brown pigment, regarded them as two 
accessory or lateral eyes in Phalangium opilio, Linn. (P. parie- 
tinum, De Geer)t. The external orifices of the sacs were 
taken by him for the cornez of these supposed eyes, although 
Latreille several years before had recognized their true nature, 
but certainly referred to them, without any clearly apparent 
* Leydig, “Zur Anatomie der Insekten,” Miiller’s Archiv, 1859, p. 69 
et seq., pl. 2. fig. 19 (Musca vomitoria) sie 3. fig. 26 ( Tabanus bovinus). 
+ G. R. Treviranus, Vermischte Schriften, vol. i. p. 25. 
