678 SUMMARY OF CURRENT RESEARCHES RELATING TO 



MycorMza-forming Fungi.* — Herr F. Noack finds the stratum of 

 tumus beneatli the peridium of Geaster fimhriatus, which is abundant 

 in pine-woods, to be penetrated by coral-like rootlets of Abies excelsa or 

 Finns si/lvestris, and these to be invested and permeated by a true 

 mycorhiza springing from the Geaster, the filaments of which vary in 

 thickness between 0*3 and 9"0/x. The following is the history of 

 development of the mycorhiza. 



The exceedingly fine hyaline unseptated hyphfe of the mycele unite 

 into thick bundles coloured white by concretions of calcium oxalate, 

 resembling in these respects the structure of young peridia. The 

 hyphfe increase in diameter, and become septated, loop-cells being at 

 the same time also formed, and they gradually become covered with a 

 dense clothing of papillae. When the rootlet of a conifer j^enetrates 

 into this mycele, it becomes entirely enveloped by a felt of hyphse, 

 forming a pseudo-parenchyraatous cap over the tip of the root. The 

 root-cap and the root-hairs of the root then nearly or entirely 

 disappear, and it branches into the well-known coral-like form. Geaster 

 forniratus forms a similar mycorhiza, but not G. striatus. 



The mycele of the following fungi has been observed by Herr Noack 

 to form mycorhiza : — Agaricus (^Tricholomd) Eussula on beech ; A. (T.) 

 ierreus on pine and beech ; Lactarius piperatus on beech and on Quercus 

 peduncidata ; L. vellereus on beech ; Cortinarius callisteus on pine ; G. 

 cserulescens on be; ch ; C. fulmineus on oak. Experiments on species of 

 Lycoperdon, Scleroderma, and Amanita all produced negative results. 



Structure of Saprolegniaceae.f — Prof. M. Hartog has carefully 

 examined the structure of the Saprolegniacese in the cases of Saprolegnia 

 Thurett, torulosa, and corcagiensis n. sp.. Leptomitus Incteus, and AcJiIya 

 prolifera and recurva. He finds the nucleus to be always vesicular, con- 

 taining a large central mass of nuclein surrounded by a less refringent 

 layer of hyaloplasm. The nucleus is usually situated in the parietal 

 layer of protoplasm, but may also be found in the strands which traverse 

 the cavity in the larger filaments. The protoplasm contains proteina- 

 ceous particles or microsomes. The apex of the filament, whether 

 vegetative or re; roductive, contains no nucleus, but a homogeneous 

 hyaloplasm without vacuoles or microsomes. Ihe nuclei divide by 

 constriction, but the phenomena of karyokinesis may also be observed. 

 The formation of zoospores is not preceded by division of the nucleus, 

 . but consists essentially of a segregation of the apocytal protoplasm into 

 distinct cells. The so-called vacuoles in the young oogone are rather 

 nuclei in every stage of conjugation. Achlya prolifera and recurva are 

 truly parthogenetic, the " s^ermamcebse " of Pringsheim being in reality 

 parasitic organisms. 



Germination of Teleutospores;.:!: — Dr. P. Diefcel enumerates the 

 species of UredineaB, the teleutospores of which germinate on the living 

 host-plant immediately after maturing, and which can therefore i)roduce 

 several teleutospore-generatious in succession in the course of one year. 

 Exclusively of the subgenera Leptojniccinia, Lepturoviyces, and Lepto- 

 cJvnjsomycca, of Pnccinia, Uromyces, and Chrysomyxa resj)ecfcively, only 

 one other species is known, viz. Hamaspora Ellisii. The author sums 



• Bot. Zto:., xlvii. (18?9) pp. 389-97 (1 pi.). 

 t Comptes Rendus, cviii. (18S9) pp. 687-9. 

 X Bot. Centralbl., xxxviii. (1889) pp. .577-81, 609-12, 657-60. 



