ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
625 
phageal ganglion of Lithobius is a brain. The ventral cord is analogous 
in function to the spinal cord of some of the lower Vertebrates. 
Production of Light in Orya barbarica.* — M. R. Dubois has studied 
the mechanism of the production of light in this Myriopod. He finds 
that it is secreted by special organs, and can be collected in a pure state. 
It is found in unicellular hypodermic glands, which are pyriform in 
shape, 8-10 mm. long and 5-6 mm. wide. Sections one-hundredth of a 
millimetre in thickness, stained with methylen-blue or haematoxylin, 
reveal the presence of numerous rounded or ovoid drops in the granular 
glandular protoplasm. These drops blacken with osmic acid, and 
exhibit the histo-chemical characters of protoplasm or of condensed 
albuminoid bodies. Soon after contact with free air a highly refractive 
point appears at their centre, and this point becomes the centre of a 
crystal or rather of a group of crystals. The encrusted protoplasmic 
matter passes, under the eyes of the observer, from the colloid to the 
crystalloid state, while light is produced. While contact with air is 
necessary and excites the luminosity, contact with water is no less so. 
The author considers that we have here to do with two successive stages 
of the photogenous material, and for them the name luciferin may be 
retained until the atomic structure has been determined. 
5. Arachnida. 
Habits of Living Scorpions. j — Mr. R. I. Pocock has some interest- 
ing notes on the habits of living Scorpions, two species of which — 
Parabuthus capensis and Euscorpius carpathicus — he has kept in captivity 
for some months. With regard to the latter he is able to confirm many 
of the observations of Prof. Ray Lankester. Though sluggish during 
the day they could always be roused by the application of a little arti- 
ficial warmth, but more than very little heat was sufficient to throw 
them into a state of the greatest consternation. Parabuthus , like Prio- 
nurus, digs shallow pits or holes in the sand, but Euscorpius was never 
observed to do so. All scorpions appear to be carnivorous ; they are 
very adroit in seizing anything that comes within reach ; they never 
seem to need anything to drink, unlike Spiders, which are very thirsty. 
The only one of the higher senses that appears to be well developed is 
that of touch ; and Mr. Pocock cannot substantiate the statement of 
M. Becker that sight and hearing are excessively developed. At a 
distance of more than three or four inches they cannot see a moving 
body. The accusation of infanticide appears to be groundless, and as to 
the charge of being suicidal, the author is as sceptical as Prof. Morgan, 
who some years ago made some observations on South African Scorpions, 
and various other authors. 
Parasitism of Pseudoscorpions.J — Prof. F. Leydig expresses his 
opinion that the presence of Pseudoscorpions on the bodies of other 
Arthropods is a case of real though temporary parasitism. In the case 
of a Brazilian beetle with a dense chitinous carapace the Pseudoscorpion 
was found below the membranous wings and the abdomen ; that is to 
say, at a point where the beetle was vulnerable. 
* Comptes Rendus, cxvii. (1893) pp. 184-6. f Nature, xlviii. (1893) pp. 105-7. 
X Zool. Auzeig., xvi. (1893) pp. 36 and 7. 
