40 J. T. CUNNINGHAM. 



dermis, glands, branchial epithelium, muscle, cartilage, &c., 

 of the Salamander larva, or adult, stained with haematoxylin 

 or safFranin, fixed with chromic or picric acid. The fibrils 

 exhibiting the phenomenon were not common in such speci- 

 mens, but appeared the more commonly the better the con- 

 ditions for studying the individual fibrils. It is necessary 

 to have division figures of large size and clearly stained, and 

 the fibrils must be as free as possible from one another. Dr. 

 Pfitzner believes that the granular structure is normal, and 

 that it is generally obscured by physical causes during 

 ordinary processes of preparation ; he found that most 

 methods of embedding altered the structure of the fibril ; 

 it was best preserved in sections of the epidermis, procured by 

 fastening pieces of the fresh skin of the larva, by means of 

 elder pith, in a microtome. Such sections were first treated 

 with 1 per cent, gold -chloride solution, and then either ex- 

 posed to light in 5 per cent, formic acid solution, or stained 

 with heematoxylin or saff'ranin, or first exposed to light in 

 the formic acid and then stained. Some fibrils he dis- 

 covered to consist of a double row of spherules ; this state 

 corresponds with the longitudinal splitting observed by 

 Flemming. 



A large portion of the paper is devoted to the support of 

 the startling proposition that these chromatin spherules are 

 individual molecules in the chemical and physical sense of 

 the Avord. This idea is based on the argument that the more 

 highly differentiated a living substance is the higher is its 

 molecular weight, the larger the number of atoms the molecule 

 contains, and the greater its size. Proceeding on an assump- 

 tion so slenderly supported. Dr. Pfitzner attempts to develop 

 a theory of the whole process of life and division in the cell, 

 but his pages are scarcely less difficult to comprehend than 

 the phenomena they are intended to explain. 



Klein's view that the intranuclear network is continuous 

 wath that of the cell is supported by Prof. C. Frommann, of 

 Jena ('Jenaische Zeitschr.,' Bd. 14, 1880), who has con- 

 vinced himself that there is no membranous envelope en- 

 closing either the nucleus or the cell itself. The contours 

 seen round the nucleus and the cell are due to the presence 

 of superficial fibrils (Grenzfaden), which run for a longer or 

 shorter distajice along the surface, and are connected by 

 other fibrils with the contiguous networks. 



Klein studied indirect division in the epithelial cells of the 

 bladder of the newt, in the lower layers of the epidermis of 

 the sheep, and other structures. According to his results, 

 the star- and wreath-form of the mother nucleus are of only 



