ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 319 



kinetic figures was seen ; the blood was excessively rich in colourless 

 cells, and had a yellowish-white colour ; of several thousand cells, it 

 was computed that only one per thousand exhibited karyokinesis. 

 From this it may be concluded either that in leucocyth^mia the 

 colourless cells multiply by direct constriction of the nucleus, or that 

 indirect cell-division chiefly occurs in the spleen and osseous medulla, 

 so that it is only rarely that cells are caught dividing in the blood 

 itself. Dealing with some deviations from the ordinary mode of cell- 

 division in sarcoma and carcinoma, the author takes the opportunity 

 of insisting on the fact that as an ordinary rule, nuclear division is 

 on the same type in man as in the Amphibia. 



Summing up the results at which he has here arrived, Flemming 

 finds that in difierent objects — ovarian cells, plant-cells, and human 

 epithelia — he has again been able to demonstrate that the physical 

 processes and the corresponding mechanics of kinetic nucleus-division 

 is, or appears to be, everywhere essentially the same ; at any rate, 

 there is no reasonable ground for doubting this uniformity. He then 

 passes in detailed review the doctrines of Strasburger, a resume of 

 which it is impossible to give here. The author states that he sees as 

 yet no ground for doubting that the nucleus is a division-organ for 

 the cell, whether or no it has other functions in addition. This view 

 is the only one which exj)lains the general presence of the nucleus and 

 the complicated kinetic processes of division. The phenomena ob- 

 served in the nucleus may lead us some day to a true physiology of 

 cell-division, and everything which bears, howsoever slightly, on 

 this point, appears to be of much more importance than any merely 

 morphological facts. 



In using the term "homology of the processes," no reference has 

 been imagined to phylogenetic considerations, and if serious objection 

 be taken to its use, we have only to replace it by " homotypy." The 

 questions raised in this connection by Strasburger have no importance 

 for the histologist. 



Theory of Amoeboid Movements.* — Mr. J. B. Haycraft endeavours 

 to account for the throwing out and subsequent I'etraction of the 

 pseudopodia (of white blood-corpuscles and unicellular organisms), 

 " pointing out, it may be, but one factor, but that a probable one." 



The author's suggestion is that in those corpuscles which exhibit 

 amoeboid movements, they are due to contractions of the stroma or 

 network of the protoplasm, which contracts at every part except where 

 the pseudopodium springs from, forcing the interstromal matter at 

 this point through the aperture left patent. 



" This accords well with the fact that the pseudopodia seem 

 actually to be projected always as radii from the cell, and that they 

 are of a very hyaline nature. The difficulty is to comprehend the 

 forces engaged in their retraction. There are probably at least 

 three: — (1) the relaxation of the stroma; (2) the viscosity of the 

 substance ; and (3) surface tension, in virtue of which a body tends to 

 assume the spherical shape. 



* Proc. Koy. Soc. Edin., xi. (1881) pp. 29-33. 



