ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1 I 



their transmission under persisting conditions to subsequent genera- 

 tions. 



Following the ancient attempts of Beguelin (1749), and numerous 

 more elaborate expedients since proposed, Gerlach introduced an air- 

 tight glass window in an aperture formed by breaking a portion of the 

 egg-shell at the pointed pole. A permanent window was, however, in- 

 convenient for experiment, though most useful for demonstration. After 

 trying half-a-dozen different instruments, Gerlach at length devised the 

 apparatus which he has used for about a year, and which he calls the 

 Embryoscope. Generally, the contrivance consists of a metal ring 

 fastened on the egg-shell, and of an air-tight glass plate covering the 

 space where the shell had been removed within the metal ring. The 

 operation is accomplished with antiseptic precautions. The window can 

 be easily opened and reclosed so that the embryo may be subjected to 

 experimental influences. For demonstration purposes, for watching the 

 , differences of growth in various regions, for studying heart-beat and 

 other functions, and above all for investigating the operation of external 

 influences, the device promises to be indispensable. Embryos with such 

 windows have lived as long as thirteen days, over half the period of 

 hatching. On till the fifth day the embryo could be readily brought 

 under the window. When the embryo itself could no longer be directly 

 observed from the window, the circulation of the blood could be caught 

 sight of, and the life of the embryo proved. 



Gerlach watched the effect of localized heat and cold, of mechanical 

 pressure, and of chemicals. He watched the appearance of bifurcation or 

 anterior doubling of the heart, and the diminution or entire disappearance 

 of the amnion. By hindering the development of the primitive streak, 

 he tried to find out whether the blood-elements came from mesoderm 

 plates or from parablast. His results were, however, too few and 

 negative to admit of certain conclusion. He was able to show that the 

 heart may go on beating two or three days after the death of the 

 embryo. The amnion may survive still longer. The retarding influence 

 of chloral hydrate on segmentation, and other facts were noted by the 

 aid of this useful contrivance. 



B. Histology.* 



Morphology of the CelLf — Dr. S. M. Lukjanow has studied the 

 intimate structure of the glandular and epithelial cells in the mucous 

 membrane of the stomach of Salamandra maculata. His research is 

 accompanied by a prodigal wealth of illustration, forming seven 

 coloured plates. 



(1) The cylindrical epithelial cells and the glandular elements 

 inclose a large number of paraplasmic structures which are very similar 

 in the two sorts of cell. One and the same cylindrical epithelial cell 

 may include different kinds of accessory nuclear body, and also mucus 

 spheroids of various kinds. The deep glandular cells show a distinct 

 tendency to produce accessory nuclear bodies and zymogen granules ; 

 the more superficial tend to mucinoid metamorphosis, only the cells of 

 the limiting zone can be placed almost without limitation on the same 

 morphological level as epithelial cells. 



(2) The extra-nuclear paraplasmic inclosures consist of the same 



* This section is limited to papers relating to Cells and Fibres, 

 t Arch. f. Anat. u. Physiol. (Physiol- Abth.), Suppl. Bd., 1887, pp. 6C-90 (7 pis.). 

 1888. C 



