ZOOLOGY AND BOTANY, MICROSCOPY, ETC. .",07 



three divisions, proto-, deuto-, and trito-cerebrum. These are blended 

 into one in the Myriopoda. The three divisions correspond to three 

 sense spheres ; the protocerebrum to that of the eyes, the deutocerebrurn 

 to that of the antennae, and the tritocerebrum to that of Tomosvary's 

 organ. 



Structure of Ocelli in Periplaneta and Cloeon.* — W. v. Reitzenstein 

 finds that in both these forms the ocellus (" fenestra ") is a three-layered 

 eye which arises through invagination of the hypodermis, and from the 

 middle layer of which the inverse retina is differentiated. The develop- 

 ment in Vespa is similar. 



Inheritance of Acquired Characters in Insecta.f — E. B. Poulton 

 discusses the evidence derived from the study of various phenomena from 

 the Insecta bearing upon this problem. Some of the points dealt with 

 are the origin of the pupal groove which receives the silken loop in 

 Pierinae, the effect of gravity upon the shape of suspended pupas such as 

 those of the Nymphalinas, various protective resemblances, and instincts 

 in Insects. The conclusion drawn from the whole is that nowhere in the 

 Insecta is there support for the assumption upon which the Lamarckian 

 theory is founded, that acquired characters are transmissible. 



Development of Head Skeleton in Blatta.J — W. A. Riley has 

 investigated the relations of the sclerites of the adult Blatta to the 

 primitive segments. He concludes that sclerites originate from mechan- 

 ical causes, and do not necessarily have any relation to the primary 

 segmentation. Their value as an index to relationship among insects is 

 not, however, depreciated. They are to a marked degree constant, and 

 may be homologised in the different groups. 



Digestion in Cockroach.§ — Dimitri Neniukoff has studied the 

 digestive processes in Periplaneta orientalis from the chemical side. 

 The salivary secretion, always neutral in reaction, changes starch into 

 glucose, has a slight peptonising function, and contains Rhodaukalium 

 (KCNS). The crop-extract changes starch into glucose and has a very 

 slight peptonising power. The mid-gut has normally an alkaline 

 reaction and an energetic proteolytic ferment. 



Palaeozoic Cockroaches. || — E. H. Sellards has studied the structure 

 of palaeozoic cockroaches and describes a number of new forms. Cock- 

 roaches represent a remarkably persistent type. They range from the 

 Carboniferous, and doubtless took their origin somewhat earlier. The 

 group has by no means remained stationary throughout its long 

 existence, but 'illustrates the laws of advance and specialisation. 



The author shows how the cockroaches afford illustration of (a) 

 specialisation by reduction, e.g. in the shortening of the ovipositor and in 

 the more or less complete fusion of two or more of the main veins at 

 their base or throughout a part of their course ; {b) parallel evolution, e.g. 



* Zool. Jahrb., xxi. (1904) pp. 161-SO (2 pis.). 



t Trans. Entomol. Soc. (London, 1904) part v., pp. civ.-cxxxi. 



X Amer. Nat. xzzviii. (1904) pp. 777-810. 



§ Physiologiste Russe, iii. (1904) pp. 31-4. 



'i| Amer. Journ. Sci.. xviii. (1904) pp. 213 27(37 figs., 1 pi.). 



V 2 



