RECENT ADVANCES IN SCIENCE 217 



frequently show fasciation of the axis and variability gener- 

 ally than those which are normal. 



Anatomy and Cytology. — Dr. R. C. Davie summarises the 

 results (Ann. Bot. April) of his examination of the pinna 

 traces of Ferns in ninety genera and over 200 species. One 

 hundred and twenty-six species show the marginal type of 

 pinna trace and 96 species the extra-marginal type in which 

 the pinna traces arise from the back of the leaf trace margin. 

 In a few genera, viz. Balantium, Leptochilus, Microlepia, Odon- 

 tosira, Coniogramme, Notholcena, and Onychium, both types 

 occur, 



M. Ishikawa Rigakushi (ibid.) describes the embryo sac and 

 fertilisation in (Enothera nutans and 0. pycnocarpa. The 

 E.S. arises from either the chalazal or micropylar end of the 

 tetrad and lacks the antipodals and one of the polar nuclei. 

 There are thus four nuclei, consisting of the remaining polar 

 nucleus, the egg nucleus, and the two synergids, as in Ludwigia, 

 Gaura, Godetia, and Circaia. Double fertilisation occurs, re- 

 sulting in a diploid endosperm. 



Ecology.— -W. H. Brown, E. D. Merrill and H. S. Yates 

 contribute to the Philippine Journal of Science (vol. xii. No. 4) 

 an account of the " Re vegetation of Volcano Island, Luzon." 

 This island is about 25 sq. kilometres in extent, surrounded 

 by the waters of Lake Bourbon, which separate it from the 

 mainland. Prior to the eruption of Taal Volcano in 191 1 the 

 vegetation appears to have been chiefly grass and small trees 

 (more especially Saccharum spontaneum and Ficus indica). As 

 a result of the eruption most of the vegetation was destroyed, 

 except in the northern part of the island, where a number 

 of bamboo clumps and some Bananas survived, relicts of the 

 former villages. 



The chief invading species in the recolonisation are grasses, 

 but even after six years the vegetation is still only sparse, 

 probably owing to erosion, the low water content, and high 

 proportion of sulphates present in the soil. The following 

 list embraces those species which are enumerated as very 

 common and widely distributed : Acacia farnesiana, Anti- 

 desma ghcesembilla (eaten by birds), Bulbostylis barbata (eaten 

 by animals), Callicarpa blancoi (eaten by birds), Eugenia jam- 

 bolana (birds and man), Ficus hauili and F. indica (both eaten 

 by birds), Ipomcea pescaprce (water), Morinda bracteata (? by 



