PSALLIOTA CAMPESTRIS 405 



examine the figure and its description in detail, a number of un- 

 satisfactory features soon make themselves apparent. It is stated 

 that "many of the tubes (hymenial elements) are sterile and are 

 called paraphyses, others produce the spores and are the basidia." x 

 In the illustration, four basidia are shown in various stages of 

 development, all protruding beyond the much more numerous 

 sterile cells and all provided with sterigmata. There is nothing 

 in the description of the figure or in the figure itself to indicate 

 whether or not any or all of the sterile elements eventually develop 

 into basidia. So far as my experience goes, the student usually 

 infers that the so-called paraphyses are destined to remain barren, 

 and so comes to the incorrect conclusion that the paraphyses are 

 much more numerous than the basidia. The basidium which has 

 discharged its spores is represented as protuberant ; but, as a 

 matter of fact, a basidium at such a stage in its history rapidly 

 collapses and sinks down to the level of the paraphyses. Collapsed 

 basidia are entirely unrepresented. There is nothing in the illus- 

 tration to indicate that the whole number of basidia develop in 

 an orderly series of successive generations. The hymenium is 

 not nearly so sharply differentiated from the subhymenium as is 

 shown, but the one passes gradually into the other. Finally, no 

 surface view of the hymenium accompanies the cross-section, so 

 that it is impossible to obtain more than a very limited idea of 

 the organisation of the hymenium as a whole. These criticisms of 

 Sachs' illustration of the hymenium of Psalliota campestris apply 

 equally to Strasburger's iUustration for Russula mibra? 



Van Tieghem 3 reproduces Sachs' figure of the hymenium and 

 states that the shorter elements (those not bearing sterigmata) 

 remain sterile and are the paraphyses, whilst the other longer 

 elements which project above the general level of the hymenium 

 (all of which in the illustration have sterigmata) are the basidia. 

 This, as we shall see, is an erroneous division of the elements, for 

 many of the shorter ones are certainly young basidia. 



1 K. Goebel, Outlines of Classification, etc. A new edition of Sachs' Text-book 

 of Botany, Book II, English translation, Oxford, 1887, p. 134. 



2 Strasburger, Schenck, Noll, and Karsten, A Text-book of Botany, third English 

 (based on eighth German) edition, London, 1908. p. 408. 



3 Van Tieghem, Traite de Botanique, Paris, 1884, p. 1049. 



