292 THE MICROSCOPE. 



De Bary has also carried out a series of experiments 

 which go far to satisfy him that the sporidia of Puccinia 

 qraminis germinate on the leaves of Rerberis, and that the 

 ^Ecidium of the JBerberis (Plate I. No. 22) is a stage in the 

 cycle of development of Puccinia. Thus, whilst in most 

 Uredines the entire development is carried out upon one 

 and the same nutrient plant, the alternate generations in 

 Puccinia graminis require a change of host. This is a 

 state of things well understood now in the animal kingdom 

 in the TaBniae and Trematoda, but Puccinia graminis is, 

 we believe, the first of the parasitic fungi in which it has 

 been particularly ascertained. Another point of interest 

 is a confirmation of the supposed injurious effect of the 

 proximity of Berberis to corn, which has been denied. 

 De Bary further shows that Mucor mucedo (the common 

 mould) has three, if not four, different forms of fruit ; and 

 that the mould called Thamnidium by Link, or Ascophora 

 degans by Corda, and the mould described by Berkeley as 

 Botrytis Jonesii, and made into a new genus by Fresenius, 

 under the name of Chcetocladium, are only varieties of the 

 fruit of Mucor mucedo. Also that yeast, Achyla, Sapro- 

 legnia, and Entomophthora or JEmpusa, are identically the 

 same as Mucor mucedo, consequently that a large reduction 

 is needed in the genera of the mucorini. 



The main interest, however, of De Bary's paper on the 

 fructification of the Ascomycetes, consists in observations 

 on Erysiphe Gichoracearum, &c., in which the author 

 traces the origin of the perithecium, from its earliest state 

 up to the formation of the single ascus and spores. He 

 notices two cells as being always present and visible from 

 the earliest period, one of which he conjectures may be 

 the female, and the other the antheridium or male organ. 

 He says that the cell, by the division of which the ascus 

 and its coating are formed, only develops itself when it 

 has been in contact with the antheridium ; and he con- 

 eiders it very probab'le that impregration is effected "by 

 such contact, and that the perithecium of Erysiphe (ex- 

 cepting the outer wall) is the product of such impreg 

 nation. 



De Bary's paper or parasitic fungi was, it appears, 

 undertaken with a view to contribute to the solution of 



