PARASITISME ET MUTUALISME—HOW FERNS GROW 825 
prec Sag recently described by Mr. Hemsley in Hooker’s Icones 
(1905, t 786). A number of seedlings which were being raised in 
oxes in ein Botanic Gardens, Trinidad, came into mate) when 
only about eight inches high, and then resumed no: h. 
The association of the flower with juvenile forms is the described 
Z 
in an cies which are oe epee ed by great poly- 
morphy in foliage, including aquatic marsh forms, such 
species of Ranunculus, Rees ag Piemadthe and others; and also 
numerous xerophytic forms. Of the latter, Dr. Diels had the 
opportunity of studying examples in Western Australia, in species 
ea and Greviilea. Xanthosia, an endemic Australian Umbel- 
lifer, numerous species of which are found in the south-west of the 
Continent, shows a remarkable variety in foliage, and the author 
of L. cernuum which has been checked in development and has pro- 
ceeded forthwith to formation of spores. 
In this little volume Dr. Diels has made a useful contribution 
to the literature of a interesting phase of plant-development. 
oi 
Parasitisme et Mutualisme dans la Nature. Par le Dr. L. Lanoy. 
8vo, pp. vili, 284, tt. 82. F. Alcan. Paris: 1906. Price 6 fr. 
Tuts forms a volume of the Bibliotheque Scientifique Inter- 
nationale, and is a semipopular account of those relations between 
plants and animals which are expressed by the terms Parasitism 
and Mutualism. The author cites various instances of parasitism 
of plants on other plants, and on animal hosis, and also of animals 
parasitic on plant-hosts and on other animals. Under Mutualism, 
o work - insects in pollination is discussed, and such phenomena 
myrmecophily. From a purely zoological point of view the 
raj dies: the form of the development of faunas and anima 
ieties. One chapter is devoted to Mimicry, the sercenzion: of 
which are drawn mainly from the animal kingdo 
A. B. RB. 
How Ferns Grow. By Marcaryt Suosson. New York: Henry 
Holt & Co. London: Bell & Sons. 1906. Pp. viii, 156. 
46 plates. Price 12s. 6d. net. 
hors have written about the external form and minute 
F . 
e prothallium or 
fertilization, and the reba ae of the embryo sporophyte; an 
