ZOOLOGY AND BOTANY, MICROSCOPY, ETC. L M .»7 



b. Histolog-y. 



Mammalian Red Blood Corpuscles.* — E. Retterer and A. Lelievre 

 find that the first-formed red blood corpuscles are large nucleated cells. 

 They disintegrate rapidly, their fragments circulate in the blood, and 

 their liberated nucleus degenerates. The definitive non-nucleated red 

 blood corpuscles are formed from the nuclei of somewhat older embry- 

 onic cells. This nucleus is transformed within the connective-tissue into 

 a small mass with haemoglobin, and the shape may be spherical, hemi- 

 spherical, oval, or lenticular. The first-formed are cells, the others are 

 transformed nuclei, and the first set does not give origin to the second 

 set. 



Integument of Voeltzkowia mira.f — W. J. Schmidt has made a 

 thorough study of the general and minute structure of the skin in this 

 lizard, discussing scales and scutes, epidermic sense-organs, pigment, 

 peripheral nerves, and the development of the integument in the re- 

 generated tail. 



Nerve-Endings in Frog's Skin. J — R. Hulanicka describes (1) two 

 kinds of free nerve-endings in the frog's skin ; ("2) the diffuse occurrence 

 of tactile cells ; and (?>) the innervation of the tactile prominences (Tast- 

 flecken of Merkel). 



Cartilage of Regenerated Amphibian Extremities.§ — K. Glaeser 

 finds that parts of the persisting tissue change into fresh cartilage, and 

 the greater part of the new skeleton is formed by a recapitulation of 

 the ontogenetic process in a cartilaginous strand. There is no produc- 

 tion of cartilage from similar tissue 



In newts a protochondral acidophilous substance arises from peri- 

 osteum-fibrils and connective-tissue fibrils (axial regeneration). A baso- 

 philous cartilage, rich in cells, arises from the cells of the periosteum 

 (peripheral regeneration). A basophilous cartilage, rich in cells, arises 

 from fresh embryonic regeneration-tissue as in ordinary development 

 (embryonic regeneration). Cartilage may also arise from the medulla 

 of the bone. 



The embryonic regeneration is independent of the place of amputa- 

 tion. Axial regeneration occurs after amputation of a small part of the 

 extremity. Peripheral regeneration occurs after amputation of a large 

 part of the extremity. 



Structure of Heart Muscle. — K. W. Zimmermann,|| Irene von 

 Palczewska,1[ and Marie Werner,** bring forward evidence, from a study 

 of the heart in Man and Mammals, in support of the old view that the 

 musculature consists of well-defined cells, in opposition to M. Heiden- 

 hain's view that the musculature in the adult heart is a reticulate syn- 

 cytium with scattered nuclei. 



* C.R Soc. Biol. Paris, lrviii. (1910) pp. 32-5. 



t Zeitschr. wiss. Zool., xciv. (1910) pp. 605-720 (3 pis. and 24 figs.). 



t Bull. Internat. Acad. Sci. Cracovie, 1909, pp. 687-9 (1 pi.). 



§ Arch. Mikr. Anat., lxxv. (1910) pp. 1-39 (1 pi. and 16 figs.). 



! Tom. cit., p. 40. 



% Tom. cit., pp. 41-100 (18 figs.). ** Tom. cit., pp. 101-48 (53 figs.). 



