ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 529 



dermis it is possible to distinguish a vasculo-pigmentary zone containing 

 pigment and blood-vessels. The latter are very abundant and run 

 exactly between dermis and epidermis. In some places the capillaries push 

 before them an extremely thin layer of connective tissue and penetrate 

 into the epidermic epithelium, which is thinner at such places. The 

 thinness may be so great that the capillary is separated from the surface 

 only by the "stratum corneum with its flattened cells. This arrangement 

 of capillaries is found over the whole surface of the body, but is 

 particularly marked on the abdomen, the top of the head, and the sides 

 of the tail. The species in question, which has the skin thus highly 

 vascularized, is also the species among pulmonate Urodela which shows 

 the greatest reduction of the lungs. It spends a part of the year in pure 

 water, cold, and usually flowing, therefore highly oxygenized. Experi- 

 ments with water containing oxygen and water partly deprived of it by 

 boiling, showed that in boded water, though bucco-pharyngeal respiration 

 was not accelerated, the newt rose more than twice as often to the 

 surface to gulp mouthf uls of air. 



Structure of Muscle-columns.* — H. Marcus discusses the conclu- 

 sion of Holmgren and Heidenhain that the muscle-columns are homo- 

 geneous on cross section. He cannot accept this view, and supports his 

 position by evidence drawn from a study of the muscles of dragon-flies. 

 The muscle-column shows (1) the elementary fibrils ; (2) the matrix ; 

 and (3) an outer limiting sheath. It is no homogeneous histomere in a 

 homoeotypic series, but a very complicated structure, as, indeed, the 

 mechanism of contraction demands. 



c. General. 



Pattern Development in Birds and Mammals.f — Glover M. Allen 

 has taken a wide survey of colour patterns. In mammals and birds 

 that are normally completely pigmented, there are certain definite points 

 of the body from which as centres the tendency to develop pigment in 

 the epidermal structures may become less and less. Outward from each 

 of these centres, pigment formation spreads to include very definite 

 areas which in wholly pigmented animals overlap slightly at their 

 borders, or are at least contiguous. 



A reduction in the area covered by any of these primary patches 

 results in a white mark at the line of junction of two contiguous colour 

 patches, where no pigment is produced. These white marks between 

 the primary patches are spoken of as primary breaks. 



By a study of the breaks in pied individuals, the author has sought 

 to define the boundaries of the primary patches in -domesticated birds 

 and mammals. They are " homologous " in the two groups. They 

 include a median crown patch, and five paired patches — corresponding 

 to the ear, neck, shoulder, side, and rump. These patches are physio- 



* Anat. Anzeig., xlv. (1914) pp. 425-9 (1 pi.). 



t Amer. Naturalist, xlviii. (1914) pp. 385-412, 467-84, 550-66 (62 figs.). 



Dec. 16th, 191 Jf. 2 N 



