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As mentioned above the young plants are unicellular but a 

 few were found consisting of a few cells (see fig. 5 e). Most pro- 

 bably the 3 cells in this figure have been torn from an old plant 

 at once. 



In the upper end of the young plant a cell division now takes 

 place, resulting in a number of cells arranged more or less regu- 

 larly (fig. 5 c). In this stage of development our plant has some 

 likeness with a small Valonia but when Schmitz also compares it 

 to a Cladophora I may point out, that I have never found any 

 specimen resembling that genus. How the cell division takes place 

 in the quite young plant (see fig. 5 c) I have not succeeded in find- 

 ing out, but I have no hesitation in assuming that it is accomp- 

 lished quite in the same way as I have found it in older specimens. 



Here the cell division was performed in the following way. 

 In some of the cells we find that the whole cell contents with 

 chromatophores, nuclei etc. have been aggregated into a number 

 of spherical clumps from three to six or even more, but most com- 

 monly three to four (fig. 5 a and 6 a). At first these spherical 

 bodies fill up far from the whole lumen of the mother cell but 

 after becoming surrounded with a membrane they begin to in- 

 crease (fig. 6 6), growing closer together and at the same time 

 becoming arranged in the same plane as the other cells in the 

 plant, which as already described by Harvey consists of a 

 single layer of cells only. When the celis are grown quite together 

 (fig. 6 c) filling up the whole lumen of the mother cell they assume 

 its form, growing polygonal, and along their uppermost and lower- 

 most edges appear the small hapters which very regularly and 

 alternately (fig. 6 f) fasten the neighbouring cells together. 



Fig. 5 b shows a transverse section of a part of a thallus in 

 which the cells have just been divided in this way. We see that 

 the wall of the mother-cell (marked x in the figure) covers over 

 the young cells and, further, we find that at each two— three or 

 four cells the cross walls of the mother cells (marked y in the 

 figure) run in between the daughter cells. On the exposed outer- 

 side or on the upperside of the flat old thallus the wall of the old 

 cells seems soon to be torn off; on the other hand, in thallus still 

 in the form of hollow sacs we often find several layers of old 

 membrane covering the sheltered innerside. 



This cell-division does not take place simultaneously in all 

 cells of the thallus; we often find, on the contrary, that it is only 



