ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 593 



but that it has become specialised ou timothy, and can only rarely be 

 induced to grow on oats and rye, and also that it has quite lost the 

 cBcidium form. 



Relation between Host and Parasite.* — Marshall Ward has 

 worked out this problem in connection with the brome grasses and the 

 Rust Puccinia dispersa that grows freely on all bronies. The paper is 

 divided into sections each dealing with some special aspect of the case. 

 After a general introduction, he discusses the different Rusts that have 

 been found on bromes. He then passes on to a description of the dif- 

 ferent species of the host plants used in this research, with an account 

 of the sterilisation and germination of the seeds in order to secure a 

 plant free from all trace of previous rust infection. Tests were made 

 as to the temperature of the leaves and the conditions generally affecting 

 the germination of uredospores. Methods of infection and the progress 

 of the various experiments are given in careful detail. Pot-plants were 

 used and the results wore found to be very different for different species 

 of brome. The spores taken from one species would not infect others 

 unless they were closely allied forms. In discussing these phenomena 

 the writer takes into account the varying conditions of the different 

 hosts. He describes the leaf anatomy, the number of the stomata, the 

 leaf-hairs, &c. He draws a comparison between the germination of 

 uredospores and that of pollen-grains as observed in attempts at cross- 

 breeding, and he considers that it might be possible to grow species of 

 grasses immune from rust infection. 



Monograph, of the Uredinese.t— P. and H. Sydow have issued the 

 first part of their important work on the Uredines. The whole of the 

 first volume will iuclude only the genus Puccinia. The authors have 

 not followed the usual division into sub-genera, such as Eupuccinia, 

 Heteropuccinia, &c. They consider that in the present condition of 

 defective knowledge as regards exotic species, it is impossible to so 

 classify the specimens. In order to lighten the labour of finding- 

 species in their book, they have followed an alphabetical arrangement 

 of host-plants. They begin with the natural order Composite, and the 

 first host cited is Achillea ; the last is Zoeyea, on which are recorded 

 species from Persia and Brazil. This first part is almost entirely occu- 

 pied with the one natural order. Two pages only at the end are devoted 

 to Calyceraceee. 



Rare or little known species are illustrated by outline drawings of 

 the spores. The diagnoses, where possible, have been made from original 

 material. 



Geastrae.J — C. G. Lloyd has recently issued in pamphlet form a 

 monograph of this family of Gasteromycetes. He includes the two genera 

 Geaster and Myriostoma. The latter is monotypic, and has been usually 

 included as a sub-genus of Geaster. It is distinguished by having 

 several orifices and several pedicels to the fruiting body. 



There are 22 American species of Geaster. Those exclusively 

 American are G. Moryanii Lloyd, G. deZtca/iw, Morg., aud G - radtcans 



» Ann. Bot.. xvi. (1902) pp. 233-315. 



t Leipzig, Borntraeger, 1902, vol. i. faac. 1, 192 pp. and 172 ! hga. 



X The Geastras, Cincinnati, Ohio, U.S.A., 1902, 43 pp. and 80 tigs. 



