29G SUMMARY OF CURRENT RESEARCHES RELATING TO 



" Nebenkern " and Nuclein Movements in Spermatid of Notonecta 

 glauca.* — J. Pantel and R. de Sinety state the three theories as to the- 

 origin of the Nebenlcem and find support for the view of Meves. 

 The formative material of the Nebenlcem is the product of a very 

 precocious differentiation, which may be seen even in the spermatocyte 

 of the first order. It is due to mitochondrial bodies appearing in the 

 cytoplasm. 



The authors discuss the exchange of nuclein or nuclein-elements 

 between the nucleus and the body of the cell, and the exchanges between 

 nucleus and acrosome. 



The nuclein movements which occur in the male cell in the course 

 of its metamorphoses recall those in the oocyte. They are indices of 

 the intricate process of sexual differentiation. 



Stridulating Organs in Saltatorial Orthoptera.! — J. Regen gives 

 a detailed account of the different forms of stridulating organs in 

 Acridiidae, Gryllidae, and Locustidae. While the essential mechanism is 

 the rubbing of a toothed bar against a ridge, there are many interesting 

 differences in detail. The elytra may be rubbed against one another as 

 in Gryllidae and Locustidae, or the elytra by the hind-legs as in 

 Acridiidae, or the abdomen by the hind-legs as in Pneamora. There is 

 a long series from the simple apparatus of some female Gryllidae to the 

 complex differentiation in many Locustidae. 



Structure of Gizzard of Carabidae.l — L. Bordas describes the 

 gizzards of Carabus (3 species), Calosoma sycophanta, and Procrustes 

 coriaceus, and has been able to study the movements of the parts in the 

 process of trituration. 



Palaeozoic and Recent Cockroaches. § — E. H. Sellards describes 

 some new structural characters of Palaeozoic cockroaches. They were 

 very abundant in the carboniferous ages, and numerous specimens have 

 afforded additional information as to head, antennae, eyes, legs, hind 

 wings, abdomen, ovipositors, cerci, and even young stages. " Evolution 

 within the group, although not rapid considering the lapse of time 

 since the Palaeozoic, has been progressive and directly in the line of 

 increased specialisation and differentiation of the organs affected." 

 This is particularly well marked in the wings, which have become more 

 specialised. But important changes are noticeable elsewhere. Thus in 

 the abdomen, the terga and sterna have become modified, tending to- 

 wards a reduction of the number of abdominal segments. The genital 

 pouch has been perfected, and the ovipositors have become reduced and 

 adapted to perform a specialised function. The long ovipositor of 

 Palaeozoic cockroaches apparently indicates that this was a primitive 

 character of the Orthoptera. " In view of the fundamental and close 

 relations, it seems evident that the Palaeozoic and recent cockroaches 

 constitute two nearly related and intergrading groups of a single order 

 Orthoptera, or, more accurately, two stages in the evolution of a single 

 phylum." 



♦ Comptes Rendus, cxxxv. (1902) pp. 1359-62. 



t Arbeit. Zool. Inst. Univ. Wien, xiv. (1903) pp. 359-422 (2 pis.). 



J Comptes Rendus, cxxxv. (1982) pp. 982-4. 



§ Amer. Journ. Science, xv. (1903) pp. 307-15 (2 pis.). 



