386 SUMMARY OF CURRENT RESEARCHES RELATING TO 



8. The internal substigmatic membrane functions as a protector of tbe 

 resjiiratory apparatus. 



9. The respiratory apparatus possesses no movements of its own 

 capable of producing influx or expulsion of air. 



10. Inspiration and expiration are caused by the rhythmical movements 

 of the dorsal vessel, and during repose this is the only cause. 



11. During activity other causes aid respiration — in walking, the action 

 of the muscles on the tracheae, and during digestion the movement of the 

 alimentary tract. 



12. The intensity of respiration varies according to the temperature." 



Stigmata of Scolopendridss.* — Dr. E. Haase, who has been investi- 

 gating the ludo-Australian Cliilopoda, finds the simplest form of stigma in 

 Lithohius and Henicops ; it is distinguished by a feebly developed peritrema, 

 by a shortish cone invested by rather short setee, the absence of a si^ecial 

 closing apparatus, and by trachea; vvhich are cylindrical and open singly ; 

 a similar form is found in the young of Scolopendra and Heterostoma. This 

 simple form gave rise to both the cleft-like and the sieve-like stigmata. In 

 Cryptops the original form is still distinctly seen, while in Cormoccphalus 

 the round orifice becomes more slit-like and distinctly bounded, and the 

 simple circlets of sjiines before the orifice of the tracheae lead to the stigma 

 of the true Scolopendridse. In the latter the stigmatic cavity divides into 

 an outer vestibule and the true cone, while the circlet of spines is very 

 highly developed. 



The ear-sliaped or branchiform stigma of Otostlgma and Branchiostoma 

 is due to the oblique form of the cone along a small part of its length ; 

 on the base of the stigmata of these forms there appear a few of those 

 irregular darkly coloured patches, beset with small hooks, which are so 

 common in the Chilopoda. These patches are tlie vestiges of the primitive 

 base of the stigma, the clear surrounding parts being foimed by the gradual 

 flattening and widening out of the trachcfe ; the external orifice of tlie 

 ear-shaped stigmata is round and finely toothed at its margin, but there is 

 no 2irojecting ring. 



The sieve-shaped stigma, e. g. that of Heterostoma, may be derived from 

 this last — by supposing the floor of the stigmatic cone to become con- 

 siderably widened out, the trachcfe approximated and multiplied, and the 

 distance between the edge of the stigma and the floor of the cone gradually 

 diminished. Although the first pair of stigmata in Heterostoma may be as 

 much as 4 mm. in size, and even project beyond the plane of the body, the 

 last shows a depression of the cone, such as is typical of Branchiostoma. 

 The author has not been able to find a connecting link between the cleft- 

 like and the ear-like stigmata. As an embryonic character of the young 

 Scolopendridae we have the peculiarity that each stigma is protected by a 

 strong hook-shaped chitinous process, as much as • 2 mm. broad ; this may 

 be regarded as a fold of the pleura. It is a secondary arrangement, 

 adapted to the special conditions of their early life. 



S. Arachnida. 



Development of Spiders.j — Herr W. Schimkowitsch has attempted to 

 clear up some of the obscurity that has surrounded tlie development f)f 

 spiders. He gives an historical review of the comparatively small number 

 of important researches. No investigator has hitherto succeeded in detaching 



* Zool. Anzcig., X. (1887) pp. 140-2. 



t Arrh. de Biul., vi. (1887) pp. 515-81 (H pis.). 



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