225 



REVIEWS AND BOOK NOTICES. 



Petrology for Students : An Introduction to the study of rocke 

 under the Microscope, by Alfred Marker, M.A., F.R.S., F.Q.S, (Fourth 

 Edition, revised). Cambridge: The University Press, 1908. 336 pp. 



When this handbook was first published, thirteen years ago, it at once 

 became popular amongst students of petrology. The fact that four 

 editions have been called for in so short a time speaks well for its continued 

 popularity, JNIr. Harker, who was at one time on tlie editorial staff of this 

 journal, and a contributor to these pages, is well known to our readers 

 for the thorough and painstaking nature of his work. The present edition 

 has been revised throughout, and a number of new illustrations have been 

 added. 



Three further Hull Museum Publications have been received. The 

 first (No. 48) is an index to the first forty-seven publications, and contains 

 some two thousand references to specimens figured and described in these 

 volumes. Publication No. 51 is the 24th Quarterly Record of Additions, 

 and contains articles on mediaeval tiles discovered in Holy Trinity Churchy 

 Hull, (illustrated). Antique Forgeries, Hull's early plays of Dickens, scarce 

 engravings, etc., etc. Publication No. 52 contains Mr. Sheppard's papers 

 on Fossil Fish etc., from the Chalk, and Pre-historic Remains from 

 Lincolnshire, reprinted from the columns of the ' Naturalist.' 



* The Development of Agaricus campestris,' by Prof. (J. F.- 

 Atkinson, Cornell University.* 



In this, Prof. Atkinson discusses the origin, growth, and gradual 

 differentiation of the several parts composing the sporophor'- or ' fruit 

 body ' of A. campestri~, and, incidentally, a few other species. It is pointed 

 out that the first formation of the young sporophore is an ovate or broadly 

 elliptical ball, consisting of a collection of slender, homogeneous, densely 

 intermingled hyphal threads, surrounded by a thin layer of looker texture — 

 the universal veil. The latter continues to grow until the formation of 

 the pileus, stem, and gills has been established, when its function ends. 

 The first indication of the origin of the hymenium in the ba.U of hyphae 

 appears, in stained longitudinal sections, as two deeply-stained spots, 

 comparable to a pair of eyes ; here the h^^phal threads while still being 

 similar in outline to those of the other parts of the ball, are much richer in 

 protoplasm, hence the deeper stain. This continues as a ring around 

 the upper part of the elongated ball ; later, a cavity — the gill cavity — is 

 formed along its course, which enlarges with the growth of the young 

 sporophore. Rudimentary radial ridges begin to form on the roof of the 

 cavity simultaneously with the commencement of the differentiation of the 

 pileus and stem. 



The further development of the various parts of the sporophore is 

 closely followed and described. Previous investigations in the same 

 direction by Nees Von Esenbeck, Schmitz, Bonorden, Hoffman, De Bary, 

 Hartig, Brefeld, Worthington G. Smith, Fayod, and others are summarised 

 and discussed. So far as one can gather, very little work of this kind has 

 been done during the last twenty years. The study of the development 

 of the Hymenomycetes is much behind that of some other groups of fungi, 

 and nearly all other groups of plants. This may be partly accounted for 

 by the difficulty of obtaining material supplying the unbroken series of 

 closely successive stages of developm.ent necessary for thoroughly working 

 out the investigations. It is onl}^ on rare occasions that a series of wild 

 material can be procured, hence a cultivated form had to be resorted to by 

 Prof. Atkinson. Armillaria mellea may supply it sometime. 



C. Crossland. 



* A reprint from ' The Botanical Gazette,' University of Chicago Press. 

 1908 June I. 



