30G SUMMARY OF CURRENT RESEARCHES RELATING TO 



Locomotion of Nucula.* — Fred Vies has made a careful study of the 

 movements of Nucula nucleus. When its pedal disc is extended the 

 upper surface of the plantar sole becomes concave in the sand, and the 

 animal draws itself towards this anchor. The precise details require a 

 diagram for their exposition. In Gastropods and most Lamellibranchs 

 the locomotion is a backward propulsion from the under or latero- 

 inferior aspect of the foot ; in Nucula the process is almost the direct 

 opposite of this. 



Arthropoda. 

 a. Insecta. 



Maturation in Viviparous Aphides.f — J. P. Stschelkanovzew 

 finds that the maturation changes of the chromatin substance in the 

 summer ova of Aphis roso' take place with great rapidity and in a some- 

 what simplified fashion. The " stage of the germinal vesicle " is distinctly 

 recognisable ; the old chromatin-thread is partially dissolved ; it seems 

 to break up into several nucleoli, but the majority of these arise by 

 new formation. During the formation of nucleoli there seems to be a 

 passage of a chromatin-like substance from the cytoplasm of the ovum 

 into the nucleus, probably to form, through the mediation of the 

 nucleolar substance, organised chromatin. The new chromatin-thread, 

 from Avhich the chromosomes of the polar body arise, is formed directly 

 from the peripheral nucleoli, and shows no trace of longitudinal splitting. 



Primitive Thysanuran.f — F. Silvestri describes Anajapyx vesiculosus, 

 which is even more primitive than Prqjapyx, and is also remarkable as a 

 synthetic type. It combines characters of Symphyla and Diplopoda (the 

 pre-anal glands and the ventral vesicles), of Campodeidre (the subcoxal 

 appendices on the internal side of the stiles of the first urosternite, the 

 form of the inferior labrum and of the stiles), of Japygida? (the presence 

 of stiles on the first urosternite, the form of the maxilla?, the same 

 number of stigmata as in Parajapyx, and the longitudinal anastomosis 

 of the trachea?), and of Lepismatidre (the longitudinal and ventral 

 anastomosis of the tracheal system and the strong development of the 

 anterior intestine). 



Protective Resemblance in Insecta. § — Mark L. Sykes gives a very 

 full account of the phenomena upon which Miiller's theory of mutual 

 protection, and Bates's theory of mimicry, are based. Numerous striking 

 illustrations are given ; most of the examples are selected from amongst 

 the tropical fauna, but it is pointed out that the British Insecta include 

 amongst their numbers in all stages, many varied and beautiful examples 

 of protective resemblance. 



Structure of Tracheate Syncerebrum.||— B. Haller reviews in an 

 exhaustive manner the plan of structure and relations of the tracheate 

 syncerebrum. Very generally and briefly it may be stated to consist of 



* Bull. Soc. Zool. France, xxix. (1904) pp. 101-6 (5 figs.), 

 t Biol. Centralbl., xxiv. (11)04) pp. 104-12 (7 figs.), 

 t Aim. R. Scuola Aerie. Portici, vi. (1905) p. 15 (12 figs.). 

 § Proc Manchester Field Club, 1904, pp. 183-234 (11 pis.). 

 || Arch. Mikr. Anat., lxv. (1904) pp. 181-279 (6 pis.). 



