392 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nucleus has divided karyokinctically, it passes through the star and 

 skein forms into the network and nucleoli form again. As the volume 

 of tho nucleus diminishes, the chromatin network becomes smaller and 

 plumper, and the nucleoli present in the majority become quite large, 

 while owing to tho condensation of the chromatin network, they become 

 more and more imperceptible. In the blood of adult larvae no actual 

 nuclear figures appear, but nuclei and the same transition forms up 

 to the homogeneous stage, as in the larva). But here the atrophy 

 increases rapidly, the chromatin network becomes coarser, the nucleus 

 assumes a mulberry shape, becomes flat, and loses its power of refraction 

 and of taking up dyes more and more, until it has completely vanished. 

 Non-nucleated blood-cells are found in some animals which have fasted 

 for half a year and more. Nuclei of leucocytes in their sites of prolifera- 

 tion always present a normal structure, but outside this, various changes, 

 as rarefaction of the chromatin network, or a massing together of it. 

 If the leucocytes outside their sites of formation seem to divide directly, 

 this is to bo regarded as a pathological change, and indeed everywhere 

 where a nucleus divides without mitosis. 



Besides senile degeneration the nucleus may become altered from 

 purely pathological conditions. When the author incised the snouts of 

 dogs, rabbits, or guinea-jugs, or scratched the cornea with a needle, he 

 found that the cells between the wound and the regeneration area showed 

 changes which resembled those of senile atrophy. Sometimes the 

 morphological, sometimes the chemical decomposition of the chromatin 

 network predominated. In the nests of epithelioma the nuclei diminish 

 in volume and then lose their refractive power and capacity for staining. 

 The difference between the regeneration of epithelium under normal 

 circumstances and in inflammatory and neoplastic conditions consists in 

 the greater number of figures found in the latter. Secondly (and 

 principally) the nuclei are strikingly poorer in chromatin than in the 

 healthy parts of the same organ, and the figures correspondingly smaller. 

 Accordingly, both the cells of malignant tumours and epithelia of inflamed 

 parts present similar characters to those of embryonic cells. That para- 

 sitic disease can influence cell-structure, follows from the author's 

 observation that mould fungi affect in a characteristic and constant 

 manner the form of the chromatin structure of the "cell-nucleus. 



Segmentation in Axolotl.* — Herr O. Schultze confirms Bellonci's 

 results as to the karyokinesis of the first segmentation cells of the 

 Axolotl. 



The framework of the resting nucleus does not pass by direct modifi- 

 cation into the nuclear coil, which lies at the periphery, while the frame- 

 work is still recognizable within. It seems as if the coil originated from 

 an entirely fresh molecular grouping. In the wall of the nucleus small 

 granules (Pfitzner's granules) appear, and these seem to group themselves 

 to form the coil. 



The importance of the attractive spheres or centres is then emphasized. 

 They consist of filar and interfilar substance. The former is associated 

 with radial arrangement in the body of the cell, and the " amphiaster " 

 is most distinct at the commencement of the so-called star form of the 

 daughter nuclei. Former observations on the formation of the daughter 

 nuclei are confirmed. 



* SB. Phys.-Med. Gcsell. Wiirzburg, 1887, pp. 2-i. 



