NESTS OF PSEUDOSCORPIONES, 99 
nearly so. This tissue, unlike that of many spiders, does not tear 
with a distinct floss. Its consistency is comparable with that of 
thin silk-paper; and one would not suppose, even on exam- 
ination with a strong lens, that it was composed of separately 
spun threads. With more ample magnification the construction 
becomes more or less obvious; but it is difficult to say what the 
arrangement is. Threads in extraordinary number and closeness, 
and most of them extremely fine, are crossed and re-crossed and 
turned about in irregular confusion. They appear to have been . 
brushed on by long-continued effort, and no doubt in a viscid 
condition since they have coalesced to a large extent. The com- 
pleted tissue is entirely without interspaces. When incomplete, 
threads of varying strength, in a more or less open, irregular 
meshwork, ave observable *. 
v. 
From what part of the animal does the material for this tissue 
proceed ¢ It was supposed that the glands were in the abdomen 
and that their ducts opened near the genital aperture in numerous 
separate spinnerets. This view was started by Menge, 1855 (6); 
and it remained unquestioned for more than thirty years. Even 
after Croneberg had shown it to be wrong, restatements of it 
continued to appear, not only in text-books, but in memoirs 
dealing specially with this Order: ef. Cambridge, 1892 (17). It 
was in 1887-8 that Croneberg (12, 14) showed that the glands 
indicated were really accessories of the genital system, nail that 
the supposed spinnerets were merely part of the bristle-armature 
of the external genital-area. At the same time Croneberg found 
that in Chelifer (Chernes) there were glands in the cephalothorax 
with ducts opening in the chelicere ; and Bertkau (18), working 
during the same years and independently, made similar discoveries 
in Obisium. Both authors concluded that these were the real 
producers of the silk; and all that was required was confirmation 
from observations on living animals. Such observations, however, 
were not made; and in the meantime various considerations have 
confused the subject ; so that, as stated recently by Godfrey (29), 
the spinning in this Order is still surrounded with uncertainty. 
Menge was well known to have supported his anatomical investi- 
gations with detailed descriptions and figures; and apart from 
these he had had living animals under observation. He had 
even described the movements of an individual which made part 
of a nest under his eyes. Croneberg and Bertkau, on the other 
hand, had arrived at their conclusions on morphological grounds 
alone. On such grounds, moreover, Supino (23) had dismissed 
these conclusions, regarding the organs in question as a poison - 
apparatus, and falling back as regar ds spInning-organs on a view 
* The only previous note on this tissue known to me is by With (25). He 
examined nests of Chelifer sculpturatus Wewis, and was surprised to find that the 
threads were not independent but fused, so that a complicated system of thinner 
and thicker threads was formed. He adds that the structure. was difficult to 
explain ; and that the newly formed threads had perhaps fused before drying. 
7* 
