244 



THE CELL 



egg nucleus, but which remain isolated in the yolk, very frequently 

 give rise to peculiar, multipolar nuclear figures. They next 

 become transformed into small sperm spindles. Neighbouring 

 spindles then frequently approach each other, so that two pole 

 radiations, and consequently the centrosomes which they contain, 

 are fused together to form one. In this manner the most various 

 collections of spindles may be produced according to the amount 

 of coalescence which occurs, especially when over-fertilisation has 

 taken place to a high degree. Further the multi-radiated figure, 

 proceeding from the over-fertilised egg nucleus, may become yet 

 still more complicated in structure by the formation of male 

 nuclear spindles. 



The interesting discoveries of Denys on the giant cells of bone 

 marrow, and of Kostanecki (VI. 46) on those in the embryonic 

 livers of mammals, may be explained in a similar manner. Several 

 centrosomes, proportionate in number to the nuclei, are present in 

 the cell. Hence when the whole cell contents commence to divide, 

 several centrosomic radiations have to develop, and amongst 

 these the nuclear segments, which under certain circumstances 

 may number several hundreds, arrange themselves in peculiarly 

 branched nuclear plates, such as have been depicted by Kostanecki 

 in Fig. 132. When subsequently the mother-segments split up 

 into daughter-segments, these move off in groups towards the 



Fig. 132. Fig. 133. 



Fig. 132. Multicentrosomic nuclear division figure, with several groups of mother- 

 segments, from a giant cell from the liver of a mammalian embiyo. (After Kostanecki.) 



Fig. 133. Multicentrosomic nuclear division figure of a giant cell from the liver of a 

 mammalian embryo; the daughter-segments form several groups, which have travelled 

 tuwards the numerous centrosomes. (After Kostanecki.) 



poles of the complicated nuclear division figure, where they form 

 a large number of small spheres (Fig. 133). Later on, a nucleus 

 develops out of each sphere ; finally the giant cell splits up into 

 as many portions as there were nuclei that is to say, spheres 

 consisting of daughter-segments present in the cell. 



The observations of Henneguy (VI. 28) on Trout eggs belong to 



