and Laboratory Methods. 1625 



CYTOLOGY, EMBRYOLOGY, 



AND 



MICROSCOPICAL METHODS. 



AGNES M. CLAYPOLE, Troop Polytechnic Institute. 



Separates of Papers and Books on Animal Biology should be Sent for Review to Agnes M. Claypole, 

 N. Marengo Avenue, Pasadena, Cal. 



Atkinson, R. T. The Early Development of Minot has described the form of circu- 



'R:bM;.'"A"^"Al'»1 !7Z"^\iLtt '^"™ f°""'' ■" *' '^"'bryonic supra- 



renal and has called it " sinusoidal." 

 It consists essentially of a system of relatively large spaces of tubes (sinusoids) 

 that communicate very freely with a large vein, the endothelial walls of which 

 are in close apposition to the cells of the parenchyma without the intervention of 

 an appreciable amount of connective tissue. Sinusoids are also found in the 

 liver and pro- and mesonephros. In the liver they form a purely venous system 

 throughout life. In the suprarenal and probably also in the pro- and mesone- 

 phros they early become attached to the arterial system. In the adult supra- 

 renal the sinusoidal origin of the circulation is known by the relatively large 

 size of the capillaries and the extremely small amount of connective tissue 

 beneath the endothelium. The condition characteristic of young mammalian 

 embryos persists apparently in the adult of Amphibia. 



In 12.5-day rabbit embryos the suprarenal first appears and consists of a few 

 cords of cells lying just cephalad of the mesonephros, closely related to several 

 large sinusoids, the latter communicating freely with the cardinal vein and the 

 sinusoids of the nearby mesonephros. At thirteen days the suprarenal has 

 become much larger, the cells are close together, and the sinusoids more numer- 

 ous. Their endothelial lining can be seen and they freely communicate with the 

 cardinal vein. At fourteen days the sinusoids are smaller, probably due to the 

 rapid growth of the surrounding parenchyma. An artery comes off from the 

 aorta just above the suprarenal and passes to the opposite side of it, a branch 

 going directly to the sinusoids. 



In older rabbits the cells of the parenchyma become compactly massed, the 

 size of the sinusoids is lessened and thus resemble true capillaries, their connec- 

 tions with the vein are reduced in number. Thus it can be seen that the artery 

 becomes early attached to the sinusoids of the suprarenal, the latter rapidly 

 decrease in size and become like capillaries and lose connection with the vein. 

 This method of establishment of the arterio-venous circulation will probably be 

 found to occur also in the mesonephros. e. j. c. 



Tandler, J. Mikroskopische Injectionen mit The fact that the hardening of gelatin 

 kaltflussiger gelatin. Zeit. f . wiss. Mikros. u. f. can be delayed by the use of certain 

 mikros. Tech. 18: 22-24, 1901. ... 



salts was utilized in the process of in- 

 jecting amphibians by adding large, quantities of potassium iodide to the gelatin. 

 The mixture was made in the following way : Five grams of finest gelatin was dis- 



