X48 J- Moore, 



sponding plasma of the exterior network. The intersectional spaces 

 of this slightly staining cytoplasmic network become consequently 

 increased in size, and appear as innumerable little bodies on the 

 outskirts of the fusion. As the process proceeds they grow in size 

 and decrease in number, ultimately becoming indistinguishable from the 

 pre-existing pseudosomes. I have termed these bodies clictyosomes. 

 Both the pseudosomes and the dictyosomes are intimately bound up 

 with the formation of the spindle figure, the only difference between the 

 two being that the former arrive at conspicuous dimensions before the 

 latter. From the figures I obtained, there can. be little doubt that a 

 fusion of these dictyosomes and pseudosomes helps to build up the 

 relatively colossal size of two bodies which ultimately occupy the position 

 of centrosomes at the apices of the spindle figure; and it appears that 

 these "centrosomes" originate (i. e. in Branchipus) in six or eight 

 pseudosomes, with the cooperation of some of the dictyosomes. 



As Flemming has remarked, mitosis is not a mere change of 

 parts in the cell, the whole protoplasmic contents undergo profound 

 changes in their refractive and other properties — „Die in Mitose be- 

 griffenen Zellen sehen an solchen Objecten aus, wie von einem dunklen 

 Lack durchsetzt". ^) 



The marked granulation of the cytoplasm which accompanies the 

 final stages of mitosis in so many cells, is, I believe, a less accentuated 

 expression of the same phenomena which produce the dictyosomes in 

 Branchipus. In this animal, the process of granulation of the cytoplasm 

 is extreme; and, as a type of mitotic change, these cells are singu- 

 larly interesting. They show the enlargement of the reticulum of the 

 nucleus into a number of chromosomes, to which the pseudosomes are 

 at first related as a plurality of centrosomes. These ultimately fuse 

 to form the two bodies normal to mitosis. They show, ftirther, that 

 a process similar to the formation of the chromosomes operates in the 

 cytoplasm without, and ultimately produces a limited number of 

 dictyosomes. These dictyosomes are to the cytoplasm, as the chromo- 

 somes are to the nucleoplasm, viz. the condensed remains of an initial 



') Archiv für Mikr. Anat. Bd. XXXVII. p. 700. 



