ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 46 



o 



Abnormal Spinal Cord in Toad.* — W. M. Sinallwood describes a 

 toad in which the spinal cord was only half the normal length. A 

 section showed that the neuroccele was not central, but pushed veutrally : 

 that the grey substance was more predominant than usual ; that the 

 dorsal grey commissure was greatly enlarged ; that the dorsal column 

 was nearly double the normal size ; and that there was a small funicular 

 region. 



Experimental Edema in Frogs. t — ^ Arthur Russell Moore has 

 analyzed the factors involved in experimental edema. In the normal 

 frog the water which is being continually absorbed through the skin is 

 removed by the lymphatics and veins. AVhen a limb is completely 

 ligatured, liquid accumulates rapidly under the ligature. This liquid 

 consists of transudate and of water absorbed through the skin by 

 osmosis. Removal of the superfluous liquid is prevented because Ijoth 

 veins and lymphatics are closed. The lymph therefore tends to become 

 more and more dilute, and the muscle correspondingly swollen with the 

 continued absorption of water. In short, the phenomena of edema 

 develop below a complete ligature because lymph and tissue take up 

 water osmotically, and the avenues for its removal are blocked. In 

 the case of edema produced by a lymphatic ligature, the lymph formed 

 in the normal fashion is retained, while the absorbed water passes into 

 the capillaries and is removed. 



Reactions of Necturus.| — Mary H. Sayle has studied the reactions 

 to skin stimuli exhil)ited by Necturus maculosus, the well-known primi- 

 tive Amphibian of American fresh waters. The skin is everywhere 

 sensitive to tactile stimulation. The regions about the nostrils, gills 

 and tail are most sensitive, and the back least sensitive. The whole 

 body surface is sensitive to chemical stimuli, the leactions being 

 characteristic for the different regions stimulated. The gills are 

 usually the most sensitive region, with the nostrils and head following 

 in order. The animal is more sensitive to nitric than to hydrochloric 

 or sulphuric acid. It is least sensitive to acetic acid. It is more 

 sensitive to potassium sulphate than to potassium chloride. When any 

 region of the body is fatigued for a given chemical, it rarely responds 

 to tactile stimuli, although it usually reacts to other kinds of chemical 

 stimuli. The animal is sensitive to considerable changes in temperature. 

 All parts of the body are sensitive to hot water (70° C), but the gills, 

 head, and nostrils are the most sensitive regions. The creature is 

 negatively phototropic and comes to rest in shaded areas. Both the 

 eyes and skin are photoreceptors, and the stimulation of either brings 

 about negative reactions. The head and tail are the most sensitive 

 regions. 



Symmetry and the DifFerentiation of Species.§ — S. J. Hickson 

 notes the general association of Ijilateral symmetry with active habits 



* Anat. Record, x. (1916) pp. 515-6 (2 figs.). 



t Amer. Journ. Physiol., xxxvii. (1915) pp. 220-29. 



t Journ. Auimal Behaviour, vi. (1916) pp. 81-102 (1 fig.). 



§ Mem. and Proc. ^Manchester Lit. and Phil. Soc, Ix. (1916) pp. 1-15. 



