1624 Journal of Applied Microscopy 



obtained. In the development of the egg nucleus, no metaplasmic substance is 

 recognized, but the linin becomes very abundant. 



When the pollen tube is ruptured, the sperm nuclei still surrounded by a 

 common mass of cytoplasm, the tube nucleus, the stalk cell, some cytoplasm and 

 some starch grains are discharged into the egg. One of the male nuclei comes 

 into contact with the egg, but before the nuclear membranes of the sex nuclei dis- 

 appear the chromatin of each nucleus is resolved into a spirem. Each spirem 

 then segments into chromosomes and the two groups remain distinct until the 

 nuclear plate stage. After the first division of this nucleus the two daughter 

 nuclei present a reticular structure in which the maternal and paternal chroma- 

 tin appear completely fused. At the second division, two chromatic spirems, 

 representing respectively the maternal and paternal chromatin, again appear. 

 There are indications that the third division will be similar. The spindle fibers 

 in the first division seem to arise by a rearrangement of the achromatic nuclear 

 reticula. 



The stalk cell disorganizes in the upper part of the egg, and the tube nucleus 

 and the smaller sperm-nucleus may share its fate, but the two latter not infre- 

 quently give rise to mitotic figures of more or less definiteness. 



Wherever the chromosomes were counted in the gametophyte, the number 

 twelve appeared. Twenty-four chromosomes were counted in the first division 

 following fertilization. c. j. c. 



^ .. ,, .. ,, ,. In the first mitosis in the pollen mother 



Andrews, F. M. Karyokinesis in Magnolia 



and Liriodciidron with Special Reference to cells the chromosomes are formed as 

 the Behavior of the Chromosomes. Bot. irregular masses without the previous 

 Centralblatt. Beihefte, II : 3-9, pi. I, 1901. ° . . rr., , 



formation of a spirem. The chromo- 

 somes are generally U-shaped, though many are in the form of open or closed 

 rings or ellipses. These chromosomes split longitudinally, but in the metaphase 

 and anaphase there is no indication of a second longitudinal splitting prepara- 

 tory to the second division, and since the daughter nuclei pass into the resting 

 condition the writer believes that no such splitting occurs, and that consequently 

 the identity of the chromosomes from the first to the second division is not main- 

 tained. In the second division, the chromosomes arise by the segmentation of 

 an irregular spirem. The number of chromosomes was not determined, but as 

 many as forty-eight were counted in a single polar view. c. j. c. 



Ishikawa, C. Uber die chromosomenreduc- Prof. Ishikawa makes the preliminary 

 tion bei Larix leptolepis Gord. Beihefte announcement that in Larix leptolepis 

 zum Bot. Centralbl. II : 6-7, 1901. ...... . , ,7 



the mitotic divisions in the pollen 



mother cells occur as in Allium fistulosum, where he has described the first divis- 

 ion as an equation — and the second a reduction division according to Weiss- 

 mann's theory. The paper, with plates, will appear in the Journal of the College 

 of Science. c. j. c. 



