Morpbolocfie der Zellen, Gewebe und Organe. 213 



sieren, sind an verschiedenen Stellen erweiternde Zusätze hinzugefügt und einige 

 Anmerkungen angehängt, die im wesentlichen Literaturnachweise zur weiteren 

 Orientierung über einzelne wichtige, im Vortrag selbst berührte Gegenstände 

 enthalten. W. May (Karlsruhe). 



Hierzu: Nr. 577, 579. 



Morphologie der Zellen, Grewebe und Organe. 



588) Bonfiglio, Francesco, Über besondere Veränderungen der Ganglien- und 

 Gliazellenkerne. In: Folia neurobiol., Bd. VI, S. 442—451. 1 Taf, 1912. 



„Bei verschiedenen pathologischen Prozessen treten im Ganglienzellkerne besondere 

 ,endonucleäre Ballen' auf, die durch eine höchst differenzierte Struktur gekennzeichnet sind. 



Auch im Gliazellenkerne kommen besondere Bildungen zur Beobachtung, die höchst 

 wahrscheinlich zu besonderen Wucherungsvorgängen der metachromatischen Kernbestand- 

 teile in Beziehung zu setzen sind." V. Franz (Frankfurt a. M.). 



589) Fauil, T. H. (Toronto, University), The cytology of Laboulbenia chaeto- 

 phora and L. Gyrinidarum. In: Annais of Botany, Bd. 26, Heft 2, S. 325 — 355, 

 1912. 



This interesting cytological study confirms the opinion previously held, that the 

 Laboulbeniales are a group of Fungi belonging to the Ascomycetes. This is indicated 

 especially by the possession of au ascus closely resembling that of the latter group. 

 No antheridia were found, but the female reproductive organ consists of a uninucleate 

 carpogonium, a uninucleate trichophoric cell, and a branched trichogyne. A binucleate 

 ascogonium is finally formed from this, which buds off asci each containing a pair of 

 nuclei. These nuclei fuse, and it is probable that this is the only nuclear fusion in the 

 life cycle. No actual fusion of nuclei occurs before the fusion in the ascus, but the 

 nuclei are arranged in pairs and undergo conjugate divisions. It is probable that the 

 latter are a significaut phase in the sexual phenomena of all sac-fungi, the nuclei being 

 associated in pairs long before they finally undergo fusion in the young ascus. 



Synapsis and chromosome reduction occur immediately following the sexual fusion 

 in the ascus. Of the three mitoses in the ascus, the first is a reduction division and 

 the other two are homotypic. The writer dissents from the opinion of Harper, Fräser 

 and others, that two nuclear fusions occur in the life cycle, and agrees with Claussen, 

 that certain of the supposed sexual fusions are to be explained as conjugate divisions 

 of nuclei. Gates (London). 



590) Hume, E. M. M. (Cambridge, Newnham College), The histology of the sieve 

 tubes of Pteridium aquilinum, with some notes on Marsilia quadri folia 

 and Lygodium dicliotomum. In: Annais of Botany, Bd. 26, Heft 2, S. 573 — 587, 

 1912. 



In this discussion on the histology of sieve tubes it is showu, that in Pteridium 

 the sieve plates are traversed at the earliest stage by delicate protoplasmic threads, 

 each having a median protoplasmic node. Callus is developed as a pair of basina in 

 connection with each protoplasmic thvead. These threads meantime become bored out 

 to form a slime string, and refringent granules appear in regulär arraugement at each 

 free end of each slime string. The callus is then dissolved away. The sieve tubes 

 function perennially but apparently callus is not deposited to block them in winter. 

 This is probably because the rhizome is a subterranean organ. Gates (London). 



591) Reed, T. (London, Guy's Hospital), Some points in the morphology and phy- 

 siology of fasciated seedlings. In: Annais of Botany, Bd. 26, Heft 2, S. 389—402, 

 1912. 



After a review of the literature of fasciations, a series of experiments are described 

 in which fasciations were produced. Seedlings of various Leguminosae were chosen, 

 and it was found that fasciations could be produced in the hypogeal forms by cutting 

 off the young stem tip. Shoots then developed in the cotyledonary axils, and these fre- 

 quently showed fasciations. The epigeal forms could not be made to fasciate in this 

 way. The vascular anatomy of these fasciated structures was polystelic. The causes of 

 fasciations are classified as (1) rapid development under conditions of superabundant 

 nourishment, (2) sudden arrest of growing points by attacks of insects or fungi, and 



