1214 Journal of Applied Microscopy 



tudinal muscle fibers. The valves are not folds of the intima, but are composed 

 of masses of cells. The blood vessels, contractile and non-contractile alike, are 

 lined throughout by a homogeneous non-cellular connective tissue membrane 

 (Leydig's intima), which is sharply limited internally and externally. Outside of 

 the intima is a layer of connective tissue cells which, in the non-contractile 

 vessels contains fibrous or band-like elements in circular arrangement. In con- 

 tractile vessels this connective tissue layer contains strong circular muscle fibers 

 with characteristic nuclei. Free blood vessels are covered by the peritoneal 

 cells, which have various forms. The formed elements of the connective tissue 

 layer in silver preparations exhibit endothelial-like boundaries, and adherent 

 blood cells in the vessels resemble endothelial nuclei, hence the endothelium 

 reported by previous authors. c. a. k. 



Ritter, W. E., and Crocker, G. R. Multiplication Young stars of this species were found 



of the Rays and Bilateral Symmetry in the r • r • • ■ n 



2o-Rayed Starfish, Pycnopodia helianthoides havmg from SIX to Sixteen arms m all 



(Stimpson). Proc. Wash. Acad. Sci. 2: stages of growth. The six arms are 



247-274, pis. 13, 14, 1900. J • 1 



arranged m a group of five and a smgle 

 one, the budding zones being placed between the two and the younger arms 

 coming in simultaneously on each side of the group of five. The stars are thus 

 bilateral, but the madreporite is not a median organ. The arms arise as inter- 

 radial outgrowths of the water-vascular ring-canal and the perihsemal canals, 

 forming ambulacra and receiving radial nerves, which at first project into an 

 ectodermal pocket from the outer edge of the nerve ring. A comparison is 

 made of the position of the sixth arm and that of the larval organ (preoral lobe) 

 of Asterina. c. A. K. 



NORMAL AND PATHOLOGICAL HISTOLOGY. 



Joseph H. Pratt. 



Harvard University Medical School, Boston, Mass., to whom all books and 

 papers on these subjects should be sent for review. 



Melnikow-Raswedenkow. Pachymeningitis Hae- In his study of the normal structure 



morrhagica Interna. Ziegler's Beitrage, 28: ^f ^j^^ ^ ^j^g ^^^^j^^^ f^^^^ Weigert's 



217, 1900. ... 



elastic tissue stain of great value. In 



the inner portion of the dura the following layers can be distinguished: (1) A 

 single layer of epithelium which covers the inner surface ; (2) a hyaloid, fenes- 

 trated, elastic membrane, which varies with age and with the individual ; (3) 

 the inner capillary network ; (4) a layer of connective tissue, mixed with elastic 

 fibers. The dura mater is a peculiar formation and has nothing in common with 

 the plural and peritoneal serosae. 



Internal pachymeningitis is regarded as an inflammation. A fibrinous exuda- 

 tion occurs upon the surface of the internal elastic membrane. Organization of 

 the exudate follows ; thin-walled capillaries grow out from the capillary layer and 

 pass through spaces in the internal elastic membrane. Rupture of the newly 

 formed blood vessels is common and haemorrhage into the delicate connective 

 tissue results. j, h. p. 



