13 



Found in dead shells both near the shore in shallow water 

 or lying on the beach as well as in deeper water. 



Found in several places and is most i^robably common. 

 Geogr. Distrib. Europe, Greenland, Atlantic and Pacific coasts 

 of America etc. 



II. Siphonocladiales. 



In my paper dealing with Siphonocladus (1905) I described 

 for the first time the remarkable »ball-cell-division«, by which 

 the whole protoplasts with nuclei and chromatophores are divi- 

 ded into a number of small clumps, which are soon surrounded 

 by a membrane and grow larger filling out the whole lumen 

 of the mother-cell, which in this way becomes divided into a 

 number of small cells. Later, I have found this mode of cell- 

 division with some variation to be characteristic of several of 

 the forms belonging to the Valoniaceae. In e. g. Siphonocladus, 

 Dictyosphaeria, Striwea, Chamaedoris it is the normal mode of 

 cell-division and as described in this paper also in Cladopho- 

 ropsis and Boodlea and a tendency towards the same mode is 

 furthermore found in several other forms of the Valoniacese. 



For this curious mode of vegetative cell-division I propose the 

 name of segregative cell-division. As I have pointed out in 

 my paper on Siphonocladus, it resembles somewhat the free 

 cell-division as found in the asci of the Ascomycetes or in the 

 sporangia of several algae and fungi. But the nuclei here take 

 part in the division and the new cells (spores) have only one 

 nucleus each and finally, in the typical free cell-division in any 

 case, some protoplasm is left in the mother cell. On the other 

 hand, in the segregative cell-division all the protoplasm of the 

 mother-cell is used; the numerous nuclei arranged regularly 

 in the protoplasm are present in the mother-cell before the divi- 

 sion takes place and these take apparently no active part in 

 the division, each part of the chloroplast at the division getting 

 a number of nuclei smaller or larger according to the size of the 

 divided parts. 



Regarding the arrangement of the genera within some of 

 the families of the group Siphonocladiales rather different views 

 are prevalent. In his »Morphologie und Biologie der Algen« 



