15-i THE JOUKNAL OF EUTAXY 



that the present book has been written and from tliat standpoint it is 

 to be judged: "The intention of the following pages is to present the 

 fungus as a living individual : the scope is mainly morphological, 

 but, in dealing with objects so minute, morphology passes insensibly 

 into cytology." There can be no doubt that the morphological side 

 of the subject should be one for the student first to tackle ; with 

 morphology as a centre, cytology, physiology, classification and 

 ])athogenic fungi can be best approached. 



An introduction of thirty-three pages gives a condensed account 

 of some of the most interesting general facts concerning Fungi. 

 After a brief introductory description of the group as a whole and its 

 general reproduction, chapters are devoted to saprophytism, parasitism, 

 and symbiosis — specialisation of saprophytism and parasitism — and 

 reactions to stimuli, each of which might easily provide material for 

 a separate treatise. Following the introduction there is a general 

 account of the Ascomycetes : the various structures present in this 

 group are treated in detail, as is also the question of the cytology of 

 the ascus and sexual reproduction. Probabl}' most readers wdio are 

 conversant with the cytological researches of the last two decades Avill 

 first look up what the author has to say about the nuclear divisions in 

 the ascus, having regard to her well-known views as to the reducing 

 ciiaracter (brachymeiosis) of the third division. The account is not 

 unauly coloured nor dogmatic, but the subtle introduction of a figure 

 by Uangeard showing chromosome reductions in the divisions in 

 u.±iicubolus farfuruceus has its humour. Another controversial 

 matter in which the author has taken a leading part is treated in this 

 chapter — /. e. the question as to the number of nuclear fusions which 

 occur in the process of fertilization in the Ascomycetes. There has 

 never been any discussion as to the occurrence of the fusion in the 

 cell of the ascogenous hypha which gives rise to the ascus since 

 Dangeard described it in Ib9-A. Dangeard held that this was the only 

 nuclear fusion ; but Harper, and after him lilackman and Fraser, 

 reported a previous fusion in the ascogonium either of male and 

 female nucleus or of sister nuclei. The ground has shifted some- 

 what since the work of Claussen (19U7, 1^12 j, who, working with 

 Fyronema, denies the fusion in the ascogonium; the male nuclei pass 

 into the ascogonium, pair with the female nuclei, and they, or their 

 descendants, remain in association, the fusion in the ascogenous hypha 

 being between the members of one of these pairs. On theoretical 

 grounds Claussen's "theory" is the most attractive: two nuclear 

 fusions and two reductions would be anomalous in the Fungi, and, 

 moreover, the pairing of nuclei agrees on the whole with what we 

 know in the Uredineae, Ustilaginea?, and Eubasidiomycetes. This no 

 doubt is leading to its general adoption, and it is therefore essential 

 that such criticisms as those put forward in the present w^ork by one 

 who understands the difiiculty of interpretation should be given their 

 proper Aveight. The pairing of nuclei in the ascogenous hyphse, which 

 is at present the crux of the question, is regarded by Dame Gwynne- 

 Vaughan as a sign of rapid growth and division, as suggested by 

 Welsford. Another point of much academic interest treated in the 

 .same chapter is that of phylogeny, as to which various theories are 



