PH.EOSPOREsE 249 



Goebel has observed their conjugation in Giraudia sphacelarioides (Derb.) 

 and Ectocarpus pusillus (Griff.), Berthold in E. siliculosus (Ktz.). The 

 process is thus described by Berthold. There is no apparent difference 

 between the male and female 'gametes. The female swarm-spores lose 

 their cilia and come to rest first. They appear to be in a receptive 

 condition only for a few minutes, during which time they seem to exer- 

 cise an attractive force on the male gametes, which swarm round them 

 until coalescence takes place. The impregnated gamete immediately 

 clothes itself with a cell-wall, and proceeds to germinate. If unim- 

 pregnated it will still germinate, though not so rapidly ; as also do the 

 male swarm-spores which fail to conjugate ; but in this case the resulting 

 hew individuals are weakly, and soon perish. This process in the 

 Ectocarpaceae may be regarded as the first stage between the conjuga- 

 tion of equivalent zoogametes and the impregnation of a passive oosphere 

 by an antherozoid. Wright (Trans. Roy. Irish Acad., 1877, p. 15) has 

 detected on an Ectocarpus a parasitic Chytridium, the zoospores of 

 which he believes to have been mistaken for sexual organs of the host. 



LITERATURE. 



Askenasy Bot. Zeit., 1869, p. 785. 



Janczewski Mem. Soc. Sc. Nat. Cherbourg, 1875, P- 97- 

 Goebel Bot. Zeit, 1878, pp. 177, 193. 

 Berthold - Mittheil. Zool. Stat. Neapel, ii., 1881. 



The TILOPTERIDE^: (Tilopteris, Ktz., Haplospora, Kjellm.) are a 

 small and ill-defined family, probably nearly related to the Ectocarpaceae. 



The SPHACELARIACE^: (Sphacelaria, Lyng., Stypocaulon, Ktz., Chae- 

 topteris, Ktz., Cladostephus, Ag.) are all small marine Algae, mostly para- 

 sitic ; ChiKtopteris plumosa (Ktz.) grows on rocks at a considerable 

 depth below the surface. The thallus usually consists of a number of 

 TOWS of cells united into a pseudo-parenchyme, and often differentiated 

 into an appearance of a ' medullary ' row surrounded by ' cortical ' tissue. 

 In Cladostephus and Stypocaulon these corticating rows of cells descend 

 to the base of the stem, and form rhizoids or organs of attachment. The 

 zoosporanges are of both kinds, and are usually placed at the ends of 

 special branches, while in Stypocaulon they are axillary ; but very little 

 is certainly known about the germination or possible conjugation of the 

 swarm-spores. The apical cell of each branch is uncorticated, and fre- 

 quently develops into a hollow chamber of considerable size termed a 

 sphacele, filled, when young, with dark mucilaginous contents, which at 

 .a later stage become watery. Geyler has described two kinds of sexual 



