130 Wisconsin Academy of Sciences , Arts and Letters. 
an der mittleren Masse gegen 100, an der aussersten fiber 200 vorkommen. 
Die Drfisenzellen sind trfibe durchsheinend, von gelblicher Farbe.” 
i( Der Bau der Drfisenmassen am ersten Hinterleibsringe von J. gigas 
wurdean Langschnittenuntersucht. Die auf der Cuticnla stehenden Har- 
chen sind gelblich und bis zur Spitze von einem weiten Kanal durchzogen, 
der scheinbar direkt in den langen Hals einer einzelligon Drfisenzelle fiber - 
geht. Die Ausffihrgange sind in der Mitte oft stark aufgeblasen, wahrend 
sie sich am Ende wieder bis zu 0,001 mm Durchmesser verschmalern. 
Aehnlich lasst sich auch bei J. solifugus der Uebergang des die hohlen 
jkurzen Haarstacheln durchziehenden Kanals in den dfinnen 0,02—0,03 mm 
langen Ausffihrungsgang einzelliger rundlicher Hautdrfisen von 0,005— 
0,008 mm Durchmesser erkennen.” 
These observations on Campodea and Japyx are of considerable interest 
in connection with the hypothesis advanced in the concluding paragraphs 
of my paper. Notwithstanding the glandular portion of the first abdom¬ 
inal segment in Japyx is broken into six clearly defined masses, it may 
still be true that originally the three glands on either side of the median 
sternal line formed only one mass. The pair of glands which might thus 
have given rise to the six separate masses mav be traced back through 
structures like the pleuropodia of Cicada to a pair of true glandular ap¬ 
pendages like those on the first abdominal segment of Campodea. Haase's 
Fig. 17, Plate XV, representing a section through the glandular mass in 
Japyx , calls to mind the pleuropodium of Zaitha. 
Haase also gives a very interesting account of the eversible sacks, 
which have long been known to occur in pairs on the ventral faces of the 
abdominal segments in many Thysanura. He has subjected both literature 
and insects to a painstaking examination, with results that I here very 
briefly summarize: In the Myriopod Lysiopetalum (two species) pairs of 
eversible sacks occur on the coxee of the 8rd-16th pairs of legs; in Poly- 
zonium germanicum and a Moluccan Siphonophora there is a pair of these 
sacks on nearly every segment caudad from the third. Scolopendrella has 
10 pairs of eversible sacks, a pair on each segment from the 3d to the 12th. 
In Campodea they are present on the 2nd to 7th abdominal segments; in 
Japyx on the 2nd abdominal segment. In Macliilis maritima and M. 
polypoda pairs of eversible sacks occur on the 1st to 7th abdominal 
segments; one large pair on the first and two smaller pairs on each 
segment from the 2nd to the 5th; the 6th and 7th segments are 
each provided with but a single pair of small sacks. Experimental 
evidence is adduced to prove that the eversion of these sacks is a voluntary 
act on the part of the insect, brought about by blood pressure, and that 
when everted these organs subserve a respiratory function. To distinguish 
them from tracheal and vascular gills Haase designates them “ Blutkiemen.” 
The study of these peculiar organs naturally leads to a consideration of 
the Collembolan collophore, to which Haase also ascribes a respiratory 
function. Since he has not yet completed his study of this organ, his 
