550 2. Elenientar-Organisationslehre. 



Major Li st on summarises bis observations on the living araoebae thus: 

 „Two distinct species of amoebae isolated from a liver-abscess have been culti- 

 valed on an agar medium. One at least of these amoebae in culture does not 

 multiply in tbe absence of living bacteria. Tbe same bacteria, when alive, 

 stimulate the amoebae to multiplication, when boiled and eaten by the amoebae 

 lack this power. Amoebae have been seen to feed upon and digest red blood- 

 corpuscles, but in the absence of living bacteria failed to multiply on agar 

 cultures". 



C. H. Martin describes preparations of these amoebae, and in a sub- 

 sequent note (p. 279 — 281) describes and figures the early stages of nuclear 

 division of one species. Doncaster (Cambridge). 



1534) Dehorne, A., Recherches sur la division de la cellule. I. Le 

 duplicisme constant du chromosome somatique chez Salamandra 

 maculosa Laur. et chez Allium cepa L. 



(Arch. f. Zellf. 6. p. 613—639. 2 Taf. 1911.) 

 Verf. vertritt an Hand einer Untersuchung normaler Zellteilungen die 

 Anschauung, daß jedes Chromosom sich von Anfang an doppelt bildet, somit in 

 jeder Telophase bereits die folgende Teilung, ja sogar die übernächste erkennen 

 läßt. Zu dieser Zeit besteht das Chromosom aus einer eng gewundenen 

 doppelten Spirale. In diesem Zustande bleiben sie während der Kernruhe so- 

 zusagen erhalten. Der sehr schnelle Verlauf der Metaphase stimmt gut mit 

 solcher Vorausnahme der Teilung überein. R. Goldschmidt (München). 



1535) Robertson, M., The Division of the Collar-cells of the Cal- 

 carea Heterocoela. 



(Quart. Journ. Micr. Sei. 57,2. p. 129—139. 1 plate. 1911.) 



The blepharoblast in Grantia and Sycon plays the part of a centro- 

 some, as previously described by the author and Minchin in Clathrina 

 (Q. J. M. S. 55,4, 1910). Doncaster (Cambridge). 



1536) Child, C. M., The Method of Cell-Division in Moniezia. 



(Biological Bulletin 21,5. p. 280—296. 16 figs. 1911.) 



This paper is the conclusion, for the present, of a controversy between 

 Child and Richards concerning the röles of mitosis and amitosis in the cell- 

 division of Moniezia. Child has examined Richard's slides and admits 

 that the early cleavages of the ovums are mitotic, either entirely, or to a much 

 greater degree than his earlier Statements would indicate. For the rest he 

 liolds his ground concerning the oecurence of amitosis. He concludes: 



„My examination of Richard's material has only confirmed me in my 

 conclusion that direct division plays an important part in the de velop mental 

 cycle of Moniezia, in the germ cells as well as in the soma. I believe I 

 have at least shown clearly enough that this material contains something 

 besides negative evidence for amitosis. 



We are, I think, not yet acquainted with the nucleus as a dynamic 

 system. We know something of it morphologically and almost all our hypo- 

 theses and theories concerning it are based on the morphological data obtained 

 from fixed material. 



But even when we consider only the results of direct Observation it is 

 difficult to understand how cytologists can continue as many do to ignore or 

 minimize the importance of the rapidly increasing number of observations on 

 the oecurrence of direct division. Certainly the work of recent years on 

 jirotozoa, to raention only this group, has brought to light many apparent 



