2064 Journal of Applied Microscopy 



quantities of rt-napthol (C J qH^OH) and para-diamido-benzene (or para-pheny- 

 lene diamine: CgH4(NH2)2) in equimolecular proportions. This solution, at 

 first colorless, becomes deeply tinted on oxidation. 2. Oxidation of dimethyl 

 p.-diamido-benzene with a-napthol ; result is an intense greenish-blue dye. 3. 

 Formation of the dimethyl derivative of quinone anilinimide by oxidation of 

 phenol with dimethyl p.-diamido-benzene. Experiments were made on the fol- 

 lowing organs and tissues of the frog : Liver, spleen, pancreas, lung, kidney, 

 testis, ovary, various parts of the intestinal tract, striated muscle, parts of the 

 nervous system,- the thymus, etc. The method was to submit thin slices of the 

 tissue (either fresh or alcoholic) to the action of the indicators until they were 

 well impregnated with the colored oxidation products. The solutions of the in- 

 dicators were made either in normal saline solution (for fresh tissue) or in dis- 

 tilled water (for alcoholic material). 



The experiments showed that, in general, oxidation takes place most rapidly 

 in those organs and parts of organs where nuclei are most numerous and most 

 densely aggregated. In the case of blood corpuscles (and also in some other 

 cells) it could be seen that the oxidation products were deposited chiefly in and 

 about the nucleus, especially at the surface of contact between nucleus and cyto- 

 plasm. The general conclusion is that •' the nucleus is the chief agency in the 

 intracellular activation of oxygen." R. p. 



Moszkowski, M. Ueber den Kinfluss der Moszkowskiconcludes after a thorough, 

 Schwerkraft auf die Entstehung und Erhal- .. , . ^. r ^i i-^ ^ 



tung der bilateralen Symmetrie der Fros- critical examination of the literature, 

 cheies. Arch. f. mikr. Anat. Bd. 6o, pp. and a series of observations and ex- 

 ^' ^ ■ periments of his own that the action of 



gravity is a necessary factor for the development of the frog's egg. The part 

 played by this force is the determination of the symmetry plane of the egg, and 

 therewith the median plane of the future embryo. This result is brought about 

 by a rearrangement of the contents of the egg (sinking of the white yolk along 

 the periphery, etc.) which takes place after the egg has been laid. While the 

 egg is within the body it occupies all possible positions with reference to the 

 direction of gravity, but the molecular cohesion of the yolk is so great that no 

 change in the relative position of yolk and other material takes place. After the 

 eggs are laid water is absorbed and the consistency of the egg substance is 

 thereby lowered. This lessening of the consistency occurs before the surround- 

 ing gelatinous envelopes have swollen enough to allow free rotation of the egg 

 as a whole, and consequently a flowing of the egg substance takes place, bring- 

 ing the heaviest constituents to the lowest point in the egg. In the case of the 

 unfertilized egg five to six hours are required for this process to take place, 

 while in the fertilized egg it is completed in from one-half to three-quarters of an 

 hour. 



If the egg in the two-celled stage is reversed (i. e., placed with the white pole 

 uppermost), and held in position by compression, not only is the symmetry of 

 the whole egg destroyed, but frequently new symmetry planes are formed in each 

 of the blastomeres. In these cases each of the first two blastomeres gives rise 

 to a whole embryo, whose organs are symmetrically arranged about the new sym- 

 metry plane. By treating the egg in the four-celled stage in the same way it is 

 not possible to produce four embryos, but instead a single symmetrical embryo 

 develops. Beyond the four-celled stage the egg, when placed in an abnormal 

 position, has no means of protecting itself from the harmful influence of gravi- 

 tation. R. p. 



