The First Abdominal Segment of Embryo Insects. 129 
While my manuscript was being copied for the printer, E. Haase's re- 
cent paper entitled “ Die Abdominalanhange der InseHen, mit Beriick- 
sichtigung der Myriopoden ” (Morph. Jahrb. Bd XV 3. Heft. p. 831-435, 
1889) came to my notice. This treatise, by far the most complete and 
accurate ever published on the subject, contains, besides a mass of other 
observations, so many interesting facts and considerations bearing on 
what has been set forth in my more special contribution, that I seize the 
opportunity to append a few paragraphs on the points of most importance 
in connection with the pleuropodia of insect embryos. 
Haase has made a study of the pair of appendages on the first abdom¬ 
inal segment of Campodea staphylinus and finds that they are specialized 
to form glandular organs (p. 378-380). These two-jointed appendages do not 
stand off at right angles to the body but are applied to its surface. The 
inner face of the broadly oval distal joint, i. e., the face turned to the 
ventral surface of the abdomen is beset with 20-30 peculiar hairs (Haaran- 
hange) arranged in rows. The two outer rows are composed of longer 
and thicker setae, arranged like the teeth of a comb. Each bristle is in¬ 
serted on a rounded follicle (Balg) which is surrounded by a ridge. A 
gland-cell terminates in each follicle. This pair of appendages is regarded 
by Haase as “ rudimentare, in der Entwicklung zurtickgebliebene 
Beine,” and hence as in no sense homologous with the ventral stylets 
(Ventralgriffel) occurring on the 2nd to 7th abdominal segments. As evi¬ 
dence in favor of this view he adduces the fact that the appendages of the 
first abdominal segment are largest in young Campodece and that their 
relative size diminishes with the growth of the insect. 
Haase makes a somewhat similar observation on Iapyx gigas and 
solifugus. In these Thysanurans no appendages are developed on the first 
abdominal segment, but in their stead six peculiar glands which are de¬ 
scribed as follows: 
“Bex Japyx gigas Brauer aus Cypern, einer Art von 23-28 mm Lange, 
tritt an der ganzen Bauchplatte des ersten Abdominalsegmentes jederseits 
des schmalen, etwas eingesenkten Mittelschildes eine flache Vorwolbung 
der Seitentheile auf. Am Hinterrande liegen jederseits des nur 0,125 mm 
breiten mittelsten Stiickes, das eine einfache diinne Duplikatur der Ven- 
tralhaut darstellt, drei scliarfbegrenzte, von einer bindegewebigen Mem- 
bran umschlossene Drusenzellmassen, welche selbst in zuriickgezogeneni 
Zustande den Plattenrand nocli iiberragen und von einer schmalen 
Ringfalte eingeschlossen sind. Die ausserste Drusenmasse isf bei 0,25 mm 
Lange 0,135 mm hoch und an den Vorderecken abgerundet. Die mittlere 
bildet einen eher abgerundet rechteckigen Korper von 0,13 mm Lange 
und 0,13 mm Ilohe; die innerste ist flach und quer gestreckt, 0.26 mm 
lang und nur 0,09 mm hoch. Die beiden ausseren Driisenmassen sind an 
ihrer freien Hinterfiache sehr dicht, die innerste sparlicher mit starren, 
spitzen, gelben Borstchen besetzt, die bis 0,03 mm lang werden und deren 
9—A. & L. 
