ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 



the protoplasmic matrix of the threads. At the nuclear-plate-stace 

 the microsomes are very indistinctly defined, in consequence of the 

 contraction of the segments and the large amount of nutrition they 

 require during the division of the nucleus ; this nutrition being 

 essentially at the expense of the nucleoli, the substance of which 

 passes over during division into that of the threads, and enters at a 

 later period into the daughter-nuclei, where it forms fresh nucleoli. 



The microsomes of animal cells show, before division of the 

 nucleus, a rayed arrangement, the amphiaster, at the two poles of the 

 future spindle. The only plant in which a similar phenomenon is 

 known is the snowdrop, where it was observed by Strasburger. As 

 regards the processes which take place in the cytoplasm during the 

 division of the nucleus, the author has observed an evident radial 

 striation round nuclei which were about to divide, and round the 

 poles of the nuclear spindle in the embryo-sac of Lilium. 



In all cases which have come under his observation the author 

 has detected the longitudinal splitting of the segments of the thread. 



Division of the Cell-nucleus in Tradescantia.* — M. E. Berni- 

 moulin gives the following process for examining the division of the 

 nucleus in pollen-mother-cells, staminal hairs, and strips of young 

 epidermis. After killing by immersion for some minutes in concen- 

 trated alcohol, the object is coloured by an aqueous solution of 

 methyl-green, then placed in dilute glycerin, and finally in more 

 concentrated glycerin. In the hairs on the filaments of Tradescantia 

 virginica he finds the striated condition of the protoplasm in the last 

 stages of the division of the nucleus, which had not been observed 

 before, approaching that found by Strasburger in the division of the 

 nucleus in the mother-cells of the stomata of Iris pumila. 



Behaviour of the Nucleus after Division.! — Dr. F. Schwarz 

 traces the changes undergone by the cell-nucleus after division, by 

 observing the appearance presented by it in a series of cells gradually 

 at a greater distance from the puncium verjetationis. The staining 

 from Beale's carmine becomes, under these circumstances, gradually 

 weaker, the size and amount of the chromatin gradually decreasing. 

 The nucleus also increases in size, changing its globular or ellipsoidal 

 to a discoid or lenticular form, finally again decreasing. The mass 

 of the nucleoli undergoes at the same time similar changes. These 

 changes are explained by the author by a hypothesis of an inter- 

 change of nutrient material between the nucleus and the cytoplasm 

 on the one hand, and between the nucleus and the nucleoli on the 

 other hand ; the nucleoli being spots in which the nutrient chromatin 

 is reproduced. 



Morphology of Chlorophyll-grains, f — Dr. A. Tschirch gives a 

 brief resume of his previously published conclusions respecting the 

 nature of chlorophyll-grains, and the grounds of his dissent from 

 some of the statements of Schmitz, Meyer, and others. 



* Bull. Soc. E. Bot. Belgique, sxiii. (1884) 8 pp. (2 pis.), 

 t Cohn's Beitr. Biol. Pflanzen, iv. (1884) pp. 79-93. 



X SB. Gesell. Naturf. Freimde, Berlin, 1884, pp. 72-7. See this Journal, iv. 

 (1884) pp. 415, 920. 



