259 



and although the two families constitutu3<^ the order differ widely 



in other particulars, this fact has been regarded as of sufficient 



importance to warrant their union into a special order. 



During the past two years the author has had occasion to 



examine more or less minutely the life-history of several forms, 



and the results reached do not support the present view. The 



investigations were made for the most part on Piliilaria glob ulif era, 



L., and Marsilia ^gyptiaca. These two plants have been made 



the subjects of especial papers which will shortly appear, and in 



which the development of the prothallium, and in Pilularia of the 



sporophyte as well, is discussed in detail, so that no attempt will 



be made here to give more than a resume of the results of the 



investigations. Salvinia nalans, L. was also examined with some 

 care. 



The resemblances between the Marsiliacem and the true 

 ferns, especially the Polypodiace^E^ has been \on^ recognized, but 

 the reduction of the prothallium, particularly the male prothal- 

 hum, was supposed to be much greater than is really the case. 



The Salviniacece^ on the other hand, differ widely both from 

 the Polypodiacece and also from the Marsiliacca, 



Before stating the conclusions reached it will be well, perhaps, 

 to glance hastily at the development of the different members of 

 the order as far as our knowledge at the present time extends. 



MARSILIACE/E. 



In this order are comprised the two genera Marsilia and 

 Pilularia^ differing mainly in the leaves and fruits, and also in 

 some minor particulars, but on the whole showing very close 

 affinities. 



The spores germinate with extraordinary rapidity, especially 

 in Marsilia, where in the case of M. jEgyptiaca, at least, within 

 thirteen hours from the time the dry spores (in somes cases twelve 

 years old !) are placed in water, at a temperature of about zd" C. 



*Hanstein, ''Bcfruchtungund EntwickeliingderGattung Marsilia," Pringsheiiii's 

 J^hib., iv., 197. Hofmeister, ''The Higher Cryptogamia/' Ray Society, 1S62, pp. 

 318-327. Hanstein, " Pilularice globulifer.x generatio cum Marbilia\;omparata/' 

 ^onn, 1866. Riissow, " Vergleichende Untersuchungen." Archaiigeli, "Sulla 



Pdularia globulifera e Salvinia natans," Nuovo Giornale Botanico Italiano, viii., 

 320. 



