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and more widely separated. At this stage each little corpuscle is 

 surrounded by a light border, which becomes especially noticeable, 

 when the corpuscles separate from the nucleus. 



During mitosis the two corpuscles are found at the tops of the 

 spindle and hence may well be called centrosomes. There are, 

 especially during; division, many black granules in the cytoplasm. 

 Thi~ always renders the investigation more difficult, but in the first 

 place the two centrosomes are larger than the other granules and 

 secondly they are surrounded by a lightborder. In the case of 

 animal cells their centrosome nature would not be doubted, but with 

 vegetable cells a certain amount of reserve is still very desirable. 

 We do not hesitate, however, to call these bodies centrosomes. ( >f 

 course they do not stain well in all mitoses. Any one who has 

 searched for centrosomes in animal tissues, knows, that the staining 

 of these corpuscles is difficult, even in objects which are famous for 

 them. The centrosomes of Polytrichum accordingly have achromatic 

 origin. They originate in the nucleus and divide into two in the 

 cytoplasm. 



Ikf.no describes these corpuscles as disappearing in the diaster 

 stage. This is not the case in Polytrichum. They do not remain in 

 their places, but may be found in various cells moving more and 

 more to the other side of the chromosomes, so that at last they lie 

 opposite each other among the spindle threads, which unite trie two 

 chromosome masses. When the daughter nuclei have only just been 

 formed and the chromosomes are therefore still more or less clearly 

 visible, the corpuscle lies between them; afterwards everything be- 

 comes a black mass. At the last division of the antheridial cells the 

 centrosome is also taken up in the nucleus and there is here no 

 deviation from what is found in liverworts. 



After this, such changes begin, as finally lead to the formation 01 

 the spermatozoids. 



We did not succeed in finding young sporogonia with many young 

 spore mother-cells undergoing division. 



We found, however, numerous dividing nuclei in the vegetative 

 cells of young sporogonia and hence it was not difficult to make 

 out the actual number of the chromosomes. The chromosomes are 

 small, but they are sharply differentiated and may be especially well 

 recognised in the equatorial plane. We found that the cells of the 

 sporogonium have 12 chromosomes. 



Judging from analogy with what 1- known of liverworts and 

 vascular cryptogams, it was safe to assume that in the formation of 

 the spores a reduction of the chromosomes would take place and 



