TWO BOOKS ON DIATOMS 291 



to attack. Fungi that are normally saprophytic and harmless 

 may become wound parasites and finally may develop into serious 

 pests, and thus they also add to the number and variety of diseases. 



Some two hundred different fungoid diseases are discussed by 

 Eriksson ; they comprise all the more important parasites that 

 attack cultivated plants of garden, field, or forest in these lati- 

 tudes. They are treated in systematic order, beginning with 

 bacteria, which are responsible for no small number of root and 

 stem roots, and so through the Phycomycetes to the higher orders 

 of fungi. The parasites included in each group are described in 

 popular language, which has been almost too literally translated, 

 the perithecium, for instance, being always referred to as the 

 " spore-case," the ascus as the " spore-bag." The translator gives 

 us now and again a quaint and suggestive word such as uredo 

 "sores" and puccinia "sores" for the sorus of spores that has 

 burst through the epidermis of the leaf, and she fails occasionally 

 to grasp the English equivalent, as in speaking of the cabbage 

 " trunk " ; but she has evidently given a faithful rendering of 

 Eriksson's work. 



Special attention is paid to remedial measures, and the account 

 of the life-history of each fungus describes the time and stage at 

 which it is most vulnerable, and when the treatment may be 

 applied with the greatest prospect of success. 



Eriksson is well-known as an exponent of the mycoplasm 

 theory of propagation in plant-rusts, and, as we should expect, 

 a full account is given of it in the chapter on Uredineae. He 

 insists that the reappearance year after year of Pttcciiiia graminis 

 can be accounted for in no other way : that it passes from gene- 

 ration to generation of the host-plant as a formless plasm in the 

 cells of the grain. 



The book is well indexed and well illustrated, three sets of 

 figures of rusts being coloured. It is a welcome addition to the 

 growing literature on plant diseases. A T ^ 



Two Books on Diatoms. 



Die Kieselalgen der Schtoeiz. Von Fr. Meister. Beitrage zur 

 Kryptogamenflora der Schweiz. Bd. iv, Heft 1. Pp. vi -f 

 255. Plates i-xlviii. Bern : 1912. 

 Contribuzioni Diatomologiche. By Achille Forti. Atti E. Istit. 

 Veneto Sci. Lettere ed Arti. Venezia: 1912. 

 The volume first-named above is the best of the smaller 

 systematic works on Diatoms which has appeared for some time. 

 It gives short diagnoses, full measurements, and reasonably good 

 figures of all the Diatoms as yet found in Switzerland. The 

 author has collected Diatoms in all parts of Switzerland during 

 the past ten years, and has also examined the numerous collec- 

 tions of other Swiss algologists. It is obvious that ho has paid 

 careful attention to specific characters and has confined himself to 

 the discussion of Swiss forms only. In this respect the volume 



