Journal of Applied Microscopy. 401 



ANIMAL BIOLOGY. 



Agnes M. Claypole. 



Separates of papers and books on animal biology should be sent for review to 



Agnes M. Claypole, Sage College, 



Ithaca, N. Y. 



CURRENT LITERATURE. 



Czermak, N. Ueber die Desintegration und The author presents in this paper some 



die Reintegration des Kernkoerperchens bei observations on the nucleolus with 

 der Karyokinese. Anat. Anz. 15: No. 22, 



pp. 414-430, 1899. reference to the changes it undergoes 



during the various phases of nuclear 

 activity. The work was undertaken to test an earlier statement, made by the 

 author in 1895, "that all elements pass through an integrating process resulting 

 in an arrangement in groups and masses, to be later scattered and more or less 

 mixed with each other." This has been demonstrated for the chromosomes 

 during karyokinesis, and these studies were planned to determine the action of 

 other cell elements. As material, the salamander testis and segmenting salmon 

 egg were used, and the results of the work, though not quite complete, are 

 presented in this paper. 



In summarizing the present status of the question, it is found that according 

 to Rhode on nerve cells the nucleoli are clearly a thickening of the nuclear 

 network. Small parts separate off and wander, with a part of the nuclear sub- 

 stance, into the cell body, become surrounded by a nuclear membrane, and 

 eventually form a new nucleus and cell. This nucleolus is here the prime 

 mover in cell division. Haecker and Reichert, in fertilization among copepoda, 

 maintain that the nucleous lies in the nuclear sap in stages when the chromo- 

 somes are fully formed, and later vanishes, from which it can be concluded that 

 it plays no important part in the karyokinesis. Metzner asserts that in the 

 spermatogonia of the salamander the nucleolus divides into many smaller ones, 

 and these scatter through the cell and apparently reassemble in the midst of the 

 daughter skein and grow to their former size. Korschelt says that in new 

 blastomeres of Ophryotrocha the nucleolus appears as a spherical mass of 

 chromatin. When the nucleus prepares for a new division, the nucleolus enlarges 

 and acquires a clearly alveolar structure, staining darkly. The chromatin threads 

 and nucleolus both reach their greatest development at the same time. The 

 nucleolus now begins to degenerate ; it becomes paler and thinner, and separates 

 into granules on the periphery, and eventually appears as a sphere filled with 

 pale granules, the result of the destruction of its network. After some of the 

 achromatin part of the division spindle appears, the nucleolus is still visible in 

 the nuclear cap. 



Omeltschenko, investigating the pancreas, liver, testis and kidney of the 

 rabbit and guinea pig, found a rod-like structure which stained in Biondi with 

 two blue spherical ends and an intermediate rose-colored ellipse. Longitudinal 

 splitting is followed by loss of the outer membrane and fibrous structure of the 

 masses, which become thicker and now stain uniformly blue, and form a 



