214 THE BOTANICAL MAGAZINE. [Vo i. xxiv. No. 284. 



ment of fungi and their effect might have been greater. Pleo- 

 sporites Shirainus Suzuki is, to understand from the general 

 habit of the group of Pleosporiacese, also more probable to 

 have been either a saprophitic one or a weak parasite. Lacking 

 further data we can not know how far the fungal damage was 

 done in the Cretaceous times. 



Another factor, which rriay be thought of, is the sulphur 

 dioxide and other injurious gases from volcanoes, which have 

 been probably much more active and extensively found in the 

 old geological periods. Such gases might have been the causes of 

 local destruction of species, just as the sulphur dioxide displays 

 its awful effect upon Coniferous forests and many other ever- 

 greens and herbs as is well known in the district near any 

 large mines, where an enormous quantity of coal is consumed, 

 even at a distance of mam' miles and in a smaller scale near 

 any railway station or factories. Dr. I. Miyake told me that 

 the very injurious effect of sulphur dioxide gas in the smoke is 

 done even in a single night when it is foggy, and Professor 

 Okamura told me that Porphyra laciniata, one of our edible 

 seaweeds, is largely damaged in a foggy day by the action of 

 smoke from factories or locomotives. Similar effect may have 

 been experienced by the vegetations of the old geological age 

 at least locally near volcanoes. 



A cause which is only applicable to seed plants may be 

 suggested by the way ; namely, the appearance of birds or 

 other animals which have learned to pick up seeds from the tree 

 and consumed the endosperm and embryo, as it is now a well 

 known case with Pinus cembra in part of Europe. 



The general cause of extinction of old plant species may 

 be well attributed to the change of climate, probably from a 

 warmer to a colder. The question about the climate of the 

 Paleozoic and other periods has been several times the subject 

 of discussions. Seward's important essay (1892) on this 

 subject gives a full account of this question. The difficulty 

 of knowing of a character whether it is really an adaptation 

 character or it is an organization character is spoken, and 

 the danger of the use of fossil plants as tests of climate of 



