ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 391 



from tea-leaves in large quantities, and from it a series of compounds, 

 which were exhibited as extremely fine preparations ; namely, the 

 salts with hydrochloric, sulphuric, and nitric acids, as also some com- 

 pounds with platinum. Adenin was found to be extremely resistant 

 to feebly oxidizing agents, but, on the other hand, to be easily acted 

 upon by reducing agents. The substances which are produced by 

 these means were not very well characterized from a chemical point of 

 view. The author, however, thinks that, owing to the ease with which it 

 can be reduced, adenin plays an extremely important part in the physio- 

 logical action of the nucleus. When adenin is reduced in presence of 

 oxygen a brownish-black substance is obtained, which appears to be 

 identical with the azocuniinic acid which is produced when hydrocyanic 

 acid is exposed to the air for a long time. In conclusion, adeuin makes 

 its appearance in large quantities under certain pathological conditions, 

 and the author has succeeded in detecting it in the urine of persons 

 suffering from leuchsemia. 



Pathological Structure of the Cell-nucleus.* — Prof. W. Pfitzner 

 draws attention to the fact that the lower we descend in the animal 

 kingdom, the nuclei are found to be so much the poorer in chromatin. 

 The same holds good for the vegetable kingdom. The development of 

 chromatin is in proportion to the stage of development of the cell. In a 

 young animal the nuclei are poorer in chromatin than in an older one. 

 A small amount of chromatin is an indication of the embryonic character 

 of the cell. Unfertilized ova of animals and plants show this poverty 

 in a very striking way. On fertilization an increase of the nuclear chro- 

 matin of the ovum occurs through the head of the spermatozoon which 

 contains a considerable quantity of chromatin, and whereby an increase 

 in the vital energy of the cell is produced. In the nuclear chromatin 

 are seen changes due to age, and these the author describes in the cornified 

 epithelium of the epidermis, and in the epithelium of the cornea and of 

 the oral cavity. The horny condition is associated with degeneration 

 of the nucleus, the chromatin substance becoming less refractive and 

 colourable, and thus disappears, or the form of the chromatic nuclear 

 constituents becomes so altered that finally it assumes the form of so 

 many separate lumps. Both processes may take place cotemporaneously. 

 Secreting cells also show nuclear degeneration. If the cell-body be filled 

 out with the secretion, the nucleus seems crumpled up, and the chromatin 

 packed closer together ; after evactiation it resumes its normal appearance. 

 In most cases effective work in a secreting cell is associated with consider- 

 able wear and tear. In sebaceous glands the nuclei of cells which line 

 the walls of an acinus show normal structure, and frequently mitosis. 

 The cells filling up the gland lumen, however, show, and more clearly 

 the nearer they are to the orifice, appearances which recall the corneous 

 cells of the epidermis ; the nucleus becomes small, round, homogeneous, 

 and loses in power of refracting and of receiving colours, and finally is 

 lost in the cloudy cell-contents. The nucleus of perfect goblet-cells 

 shows similar appearances. 



In the salamander larva karyokinesis of the red blood-cells takes 

 place in the whole of the circulatory system ; in the adult salamander, only 

 in the spleen. In the blood of the larva there are found also cells which 

 show changes due to age in addition to the fully formed cells. After the 



* Yirchow's Arch. f. Path. u. Hist. Anat, ciii. (1886) pp. 275-300 (1 pi.). 



