426 SUMMARY OF CURRENT RESEARCHES RELATING TO 



that a spindle figure can only be obtained in a field with the two unlike 

 poles of a dual force. Diffusion, osmosis, and surface tension cannot be 

 the forces involved in the spindle. Further, since an isolated magnetic 

 pole cannot exist, it is obvious that the cell-fields, being in three 

 dimensions, and with isolated unlike poles, cannot be due to magnetism. 

 It is not impossible that the field may be produced by statical elec- 

 tricity, but of this at present there is no proof. 



Studies on Chromosomes.* — E. B. Wilson finds that the chromo- 

 somes which have been called by Montgomery " heterochromosomes " 

 in Hemiptera, include three distinct forms, provisionally termed («) the 

 paired microchromosomes, or m-chrornosoines ; (b) the idiochromosomes ; 

 (c) the " accessory," or heterotopic chromosomes. The structure, re- 

 lations, and behaviour of these are discussed in the present two papers, 

 and it is concluded that the facts support the general theory of the 

 individuality of chromosomes, the theory of Montgomery in regard to 

 synapsis, and that of Sutton and Boveri regarding its application to 

 Mendelian inheritance ; and they point towards a definite connection 

 between the chromosome group and the determination of sex. 



Histology of Mammalian Nostril.f — B. jKormann gives a com- 

 parative account of the histological structure of the nasal vestibule in 

 various domestic mammals, and of the diverticulum nasi of the horse. 

 The vestibulum nasi differs as to its extent in different mammals : it is 

 covered by a many-layered flattened epithelium and with a papillary 

 body, and contains glands reaching to the sub-mucosa. These are 

 tubular glands of a serous character. The covering of the wall of 

 the diverticulum nasi of the horse is not a mucous membrane. It is a 

 direct continuation of the outer skin, from which, however, it is dis- 

 tinguished by the possession of only quite thin and weak hairs. It 

 contains numerous sebaceous glands in the corium, and abundant sweat- 

 glands in the sub-cutis. Between this integumental layer and the true 

 nasal mucous membrane, which has ciliated epithelium, there is a small 

 band of vestibular mucous membrane very rich in serous glands. 



Skin of Reptiles.^— F. Krauss has investigated the relations of 

 epidermis and cutis in Lizards and Crocodiles. He describes the de- 

 velopment of the cutis from the rete Malpighi, and notes in the skin of 

 many adult reptiles — especially in the looser connective tissue of the 

 scales — frequent suggestions of embryonic conditions. As such may be 

 quoted gelatinous tissue between the cutis and epidermis. The relation 

 between the epithelial fibres of the epidermis cells and the connective 

 tissue fibres below the epithelium is also described. 



Amphioxus Brain.§ — L. Edinger describes various hitherto un- 

 known features in the central nervous system of Amphioxus. The 

 central canal of the spinal cord shows an anterior widening — the brain 

 vesicle whose degree of development in mature animals appears to be 



* Journ. Exper. Zool., ii. (1905) pp. 371-405 (7 figs.) and 507-45 (4 figs.). 



t Anat. Anzeig., xxviii. (1906) pp. 5-16 (1 fig.). 



X Arch. Mikr. Anat., lxvii. (1906) pp. 319-63 (2 pis. and 14 figs.). 



§ Anat. Anzeig., xxviii. (1906) pp. 417-28 (15 figs.). 



