MANUAL OF TREE DISEASES 167 



the usefulness of the book may be gauged from the fact that a know- 

 ledge of what it contains as to the prevalence of " peckiness," due to 

 Fomes geotropus Cooke, in from 33 to 100 per cent, of the trees of 

 Taxodium in Florida, Louisiana and other States might — not many 

 months ago — have saved our Government many thousands of pounds. 

 Both volumes are well got up ; but publishers should submit the 

 ** jackets," in which it is now the fashion to send out books, to the 

 authors for correction, as two misprints in one brief descriptive 

 paragraph is not a good advertisement of the contents of a volume. 



G. S. BOULGER. 



BOOK-NOTES, NEWS, etc. 



At the meeting of the Linnean Society on May 1, Mr. James 

 Smith gave a demonstration of the various forms assumed by the 

 pappus in Compositce, of which the following is his abstract : — 

 Stating the case for the trichome nature of the pappus in this family 

 as briefly as possible, we have six points. 1. The development of the 

 members of the pappus is either that of a typical trichome (from one 

 epidermal cell) or that of an emergence, such as the spines of a thistle, 

 2. The structure of the mature pappus is that of a series of hairs 

 which have become fused throughout all or a part of their length, 

 either side by side to give a scale or in a mass to give an awn. 3. The 

 similarity of the setae to the achenial hairs is very marked. 4. The 

 primitiveness of the scabrid seta is in conformity with the evolution 

 of the family as deduced from other data. 5. The predominant type 

 of pappus in the fossil forms is the setose type : no fossil paleaceous 

 pappus is known. 6. The preseDce of a pappus is coiTelated or linked 

 with the presence of achenial hairs, deduction of both characters 

 is also linked, e. g. reduction of the elater hairs of the achene in the 

 Anfhemidere to special epidermal cells is accompanied by reduction of 

 the pappus to the coroniform type. The same applies to some cases 

 in the Gichoriece.. As all the facts adduced in support of the phyllome 

 theory can be easily and adequately explained by assuming that the 

 pappus in certain cases is parti}'' a development of the hairs which 

 Avere inserted on the now aborted but once free calyx-segments, the 

 evidence in favour of the trichome or emergence nature of the organ 

 a Imits of no other conclusion than that which takes the pappus to be 

 hairs, free or fixed, derived in their evolution from the hairs of the 

 ajhene, or sometimes also from the hairs of the now aborted calyx- 

 limb. 



The subject of tropical plant-diseases is extremely important, 

 seeing that we rely on the warmer regions of the earth for so many 

 r.iw products. Fungi seems to flourish there with great luxuiiance, 

 the warmth and moisture providing most favourable conditions 

 for their development. In his Pliilipjyine Economic-Plant 

 Diseases (Phil. Journ. Sci. xiii. 1918, nos. 4 & 5) Dr. Otto 

 Keinking says : " There are as many destructive plant diseases 

 in the Philippine Islands as there are in the United States, if 

 there are not more." In this work, the author has followed on the 



