312 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Development of Lung-books and Tracheae in Spiders.* — Remold 

 Janeck has studied this, especially in Lycosa ammtata, with some other 

 forms for comparison. The foldings on the under surface of the primor- 

 dium of the abdominal appendage are quite distinct from the foldings 

 which give rise to the lung-book, and the author is against the view 

 which derives lung-books from branchial organs. 



The lung-book arises from a compact cell-mass, of ectodermic origin, 

 and from an associated invagination of the ectoderm ; the tracheae arise 

 from invaginations of ectoderm, and there is often a solid proliferation 

 which subsequently gets a cavity. The author is therefore strongly in 

 favour of the view which derives lung-books from trachea?. 



Spinnerets, Cribellum and Respiratory Organs of Spiders.f — 

 Thomas H. Montgomery, jun., has studied Theridium, Loxosceles, Eva- 

 grus and Filistata. He confirms the interpretation of the cribellum as 

 a modified and fused pair of spinnerets. The colulus or hypopygium is 

 an integumentary extension with a large axial blood cavity, and may be 

 a supplementary respiratory organ. The anterior spinnerets and colulus 

 or cribellum develop from the fourth abdominal segment, the median 

 and posterior spinnerets from the fifth. The colulus and cribellum 

 arise as elongate thickenings mesial from the appendages of these seg- 

 ments, the appendages becoming the anterior and posterior spinnerets. 

 Colulus and cribellum are in their development homodynamous with 

 the median spinnerets of the segment behind them. 



Each lung-book arises in the regiou of the appendage of the second 

 abdominal segment. An ectoblastic invagination forms the stigma and 

 chamber, and into this the appendage invaginates, forming both oper- 

 culum and secondary lamella?. There are no radical anatomical diffe- 

 rences between tracheae and lung-books, but the developmental differences 

 are considerable, and there is no complete homodynamy between the 

 two sets of organs. There is no embryological ground for deriving the 

 lung-books from gills. 



Structure of Ixodes reduvius.J — Erik Nordenskiold continues his 

 account of this tick, and describes the circulatory, respiratory, and repro- 

 ductive systems. 



«. Crustacea. 



Sex-recognition in Crawfishes. § — A. S. Pearse has studied the copu- 

 lating reactions of three species of Cambarus. Males which had recently 

 been in active copulation were not necessarily induced to copulate again 

 by the immediate presence of an active female. The readiness with 

 which copulation takes place depends largely on the " chance " coming 

 in contact of two individuals which are in the proper physiological state. 

 The temperature of the water has some influence ; conditions of light- 

 stimulation are apparently of little consequence ; experiments with pieces 

 of ovary and the like lend no support to the view that there is any 



* Jen. Zeitschr. f. Natur., xliv. (1909) pp. 587-646 (1 pi. and 67 figs.), 

 t Proc. Acad. Nat. Sci. Philadelphia, lxi. (1909) pp. 299-320 (4 pis.). 

 % Zool. Jahrb., xxvii. (1909) pp. 449-64 (1 pi.). 

 § Amer. Nat., xliii. (1909) pp. 747-53. 



