ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 493 



filamentous, and which may project into the nucleus and give its 

 boundaries an irregular apijcarancc. After treatment with • 2 per cent, 

 chromic acid the nucleus generally retains sharp and refractive contours, 

 while at the same time the nucleolus becomes distinctly apparent. 



The much discussed question of the radiate figures in the fertilized 

 egg is next considered. The author does not find that they exhibit the 

 regularity which we should be led to expect from the figures and de- 

 scriptions of 0. Hertwig, Ful, and Flemming ; as in the other parts of 

 the cell-body, there are changes in these parts. The rays as well as 

 their constituent parts continually alter their form and character, dis- 

 appear, and are again built up ; these changes are described in some 

 detail. 



In embryos with from twelve to sixteen and more cells the spaces 

 between the separate cells are generally very slight ; in these granules 

 may be detected, which may possibly be cell-bridges which ajjpear as 

 granules in consequence of their shortness. When the intercellular 

 spaces are somewhat wider there are some indications of filaments. 



The changes which take place in the network of the grey substance 

 of the brain of Torpedo marmorala and B.aja asterias, and in the gan- 

 glionic cells of the Torpedo, are next considered. The changes which 

 take place in the stroma of the ganglionic cells have the same character 

 as those which occur in the grey substance — and but for their being 

 slower — as what are seen in the eggs of Strongylocentrotus lividus. They 

 also correspond in their morphological relations with what hf. been 

 observed in the blood-corpuscles of Invertebrates, the network of the 

 tentacles of Hydra, and the living cartilage-cells of the rabbit. In the 

 leucocytes of the frog not only do the nuclei disappear, and be again 

 formed from protoj)lasmic parts, but changes may take place in the 

 granular and filamentar parts of the cell-body without any new formation 

 of nuclei. Similar examples may be cited from many plants. 



New Formation of Cells.*— Dr. B, Morj)urgo finds that new cellcs 

 are formed by indirect fission, even during acute inanition of the 

 organism. Karyokinetic figures are found both in growing organs and 

 in the adult organs of animals that have died of hunger, and, therefore, 

 in organs where they give signs of a formative process as well as where 

 they represent cellular regeneration. Indirect fission, under whatever 

 conditions produced, becomes less active when there is an inanition of 

 the organism. The numerical diminution of mitoses is relatively less 

 in slightly differentiated glandular cells and in investing epithelia than 

 in highly ditierentiated glands; of these latter we may say that the 

 process of karyokinesis is almost wholly limited to the period of their 

 more active growth. Of the ditierentiated organs, the gonads alone ex- 

 hibited a process of very active karyokinesis during the inanition of the 

 organism. This shows that these organs are highly individualized even 

 in animals which are high in the zoological scale, and that they are able 

 to demand of other organs the sacrifice of a richly nutrient material. 



Relation between Cell-body and Nueleus.j — Dr. F. Tangl comes 

 to the conclusion that the sharp boundary between the nucleus and the 

 cell-body disappears when the achromatic nuclear membrane is dc- 



* Arch. Ital. Biol., xi. (1880) pp. 118-3.3. 



t Math, u, Naturwiss. Bcricht. aus Ungurn, vi. (1889) pp. Gl-77 (1 pi.). 

 1889. 2 M 



