418 Allgemeines. 



The two nuclei do not however fuse, but divide simultaneously 

 at every cell-division up to the formation of teleutospores. In 

 the latter, as they are approaching maturity, the fusion is com- 

 pleted. But this is not a delayed act of fertilisation, for the 

 cytoiogical evidence indicates that it is a mere antecedent to 

 reduction such as occurs in a spore-mother-cell. Black- 

 m a n insists on the validity of this comparison, and the grounds 

 of his argument are cogent When the teleutospore germinates 

 ät may produce i'our promycelial cells from each of which a 

 sporidium is budded off, or the sporidia may be formed more 

 directly. On the other hand, if grown in water the formation 

 of sporidia may be delayed, the promycelium continuing to 

 grow, but remaining 4-celled. For the details the original must 

 be consulted. 



A point of considerable cytoiogical interest lies in the fact 

 that a synaptic phase so characteristic of the heterotype mitosis 

 in spore mother cells, can be distinguished. 



Furthermore the first nuclear division of the teleutospore 

 is more in accordance with the ordinary processes of mitosis, 

 centrosomes and chromosomes being present. The later divisions 

 however are more nearly related to amitosis. 



The author discusses the significance of the spermatia, and 

 concludes that they represent genuine male sexual elements 

 that have become functionless. He points out that in cytoiogical 

 respects they possess many features in common with male 

 gametes, such as relatively large nuclei, and exiguous cyto- 

 plasm. The sterile cell, already referred to as cut off from 

 what may be called the aecidium-mother-cell, strongly reminds 

 one of a trichogyne which however has become functionless. 

 It does not, in the investigated species, burst through the 

 cuticle of the host-plant, and it degenerates at an early period 

 in the development of the aecidiospores. 



As regards the belated character of the fusion of the two 

 nuclei, the author shews, by citing sämilar instances from ani- 

 mals, that this cannot be urged as an argument against the 

 sexual nature of the process. Various difficulties that arive in 

 connection with the conclusions above summarised are fuliy 

 discussed in the original paper which contains many points of 

 interest that could not be usefully summarised here. 



B. Farmer. 



Hager-Mez, Das Mikroskop und seine Anwendung. 

 Handbuch der praktischen Mikroskopie und Anleitung zu 

 mikroskopischen Untersuchungen. 9. Aufl. (Berlin, Springer 

 1904. 392 pp. Mit 401 Fig. Pr. 8 Mk.) 



Neunte Auflage des bezeichneten von M e z (Halle) in Gemeinschaft 

 mit Appel (Berlin), Brandes (Halle) und S toi per (Göttingen) be- 

 arbeiteten Buches. 



Der erste Theil desselben (Theorie des Mikroskops) hat wesentliche 

 Veränderungen nur insofern erfahren, als die Theorie des Polarations- 

 Mikroskops in grösserer Ausführlichkeit dargestellt wurde. 



