ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 29 



movement, which though probably common to some extent to all the 

 cells of the embryo, is especially accentuated in the nerve-cells at this 

 period of development. 



One of his devices was to excise a piece of medullary cord about 

 4 or 5 segments long from an embryo frog, and to replace this by a 

 cylindrical clot of blood or lymph of the proper length and calibre. 

 Xo difficulty was experienced in healing the clot into the embryo in 

 proper position. After 2 to 4 days the specimens were preserved and 

 sectioned. It was found that the funicular fibres from the brain and 

 anterior part of the cord, consisting of naked axones without sheath 

 cells, had grown for a considerable distance into the clot. 



Central Nervous System of Cyclostomes.* — G. Sterzi has pub- 

 lished the first instalment of a treatise on the central nervous system 

 of Vertebrates. He deals with Petromyzon, Myxine, and Homea, dis- 

 cussing exhaustively not only the nervous system, but the associated 

 skeleton, membranes, and vessels. 



c. General. 



Sense of Touch in Mammals and Birds.f — W. Kidd has made a 

 careful anatomical study of the palmar and plantar surfaces of a large 

 number of mammals and of a few birds, with special reference to the 

 presence and the pattern of the papillary ridges. He finds that 

 the papillary ridges (which are found chiefly in Primates) are to 

 be regarded as primarily tactile in function, and only secondarily 

 as adaptations to prevent slipping. Thus they occur in places 

 where they cannot possibly help in prehension, e.g. on the extensor 

 surface of the terminal phalanges in Lemur brunneus. Further, 

 the pattern is in many cases such that the ridges cannot possibly 

 tend to prevent slipping, either in walking or prehension. The 

 increasing complexity in pattern, which finds its climax in the terminal 

 phalanges of the human hand, is to be regarded as an adaptation for 

 increasing the delicacy of the touch. Whorls are a further develop- 

 ment of loops and arches. The degree of development of the papilla? 

 of the corium depends greatly upon the importance to the animal of 

 the tactile sense ; thus lemurs have very highly developed papilla, 

 and so also have many birds, for whom maintenance of equilibrium is 

 a daily necessity. 



Hand and Foot in Hylobates agilis4 —Duncan C. L. Fitzwilliams 

 describes these with reference to form and function, indicating the 

 differences between them and the hands and feet of man. In Hylobates 

 the fingers are capable of flexion and adduction to the middle line, but 

 have little tendency to oppose the thumb, and transverse and longi- 

 tudinal creases are therefore met with. In man, opposition of the 

 thumb to the fingers is one of the most prominent characteristics of 

 the hand, and the creases, in consequence, are oblique. There is much 



* II sistema nervoso centrale dei Yertebrati. I. Ciclostomi (Padova, 1907) xiii. 

 and 731 pp., 194 figs. 



t The Sense of Touch in Mammals and Birds. London, 1907, 176 pp., 164 figs. 

 X Ann. Nat. Hist. cxvi. (1907) pp. 155-61. 



