Carter. — Studies on the Chloroplasts of Desmids. IV. 319 
West, x 510. Fig. 51 shows the division of the pyrenoid and constriction of the chloroplast 
preparatory to cell-division ; Fig. 52 shows the completed division. 
Fig- 53- Netrium Digitus, (Ehrenb.) Itzigs and Rothe. x 510. *A stage in cell-division 
intermediate between Figs. 51 and 52, showing the travelling of the two daughter nuclei towards 
the clefts between the newly divided chloroplasts. 
Fig. 54. Euastrum bidentatum , Nag. x 510. Showing division of the pyrenoid during cell- 
division. 
Figs. 55, 56. Staurastrum Brasiliense, Nordst., var. Lundellii , W. and G. S. West, x 510. 
Fig. 55, very young semi-cell seen from the end, showing that the ingrowing chloroplast even at this 
early stage preserves its five-lobed structure, although the pentangular shape of the cell-wall itself is 
scarcely to be discerned ; Fig. 56, front view of a much later stage, showing the entrance of the 
pyrenoids from the old semi-cell, and the nucleus displaced to one side. 
Fig. 57. Cosmarium Brebissonii, Menegh. x 510. Side view of dividing specimen, showing 
the ingrowth of the chloroplast and pyrenoids, and the nucleus pushed to one side. 
Fig. 58. Staurastrum anatinmn , Cook and Wills, x 510. Front view of dividing individual, 
showing the division of the pyrenoids and the rapid growth of the more peripheral parts of the 
chloroplasts as compared with that of the more central part. 
Fig. 59. Xanthidium armatum , (Breb.) Rabenh. x 510. Front view of a very early division 
stage, showing the beginning of the budding into the young semi-cell of the chloroplast together with 
its pyrenoids. 
Fig. 60. Tetmemorus granulatus, (Breb.) Ralfs. x 510. Side view of a recently divided 
specimen in which the chloroplast has entered the young semi-cell, but division at the sinus has not 
yet taken place. 
PLATE XVI. 
Figs. 61-70. Eu. Didelta , (Turp.) Ralfs. x 350. Process of cell-division followed in a single 
individual: Fig. 61, July 25th, 11.15 a.m. ; Fig. 62, 11.30 a.m. ; Fig. 63, 11.40 a.m. ; Fig. 64, 
12 noon; Fig. 65, 12.30 p.m.; Fig. 66, 2 p.m. ; Fig. 67, 5 p.m. ; Fig. 68, July 26th, 10.30 a.m. ; 
Fig. 69, 1 1.30 a.m. ; Fig. 70, July 27th, 10.30 a.m. 
Figs. 71-4. Cosmarium subtumidum , Nordst. x 1,750. Behaviour of the pyrenoid during 
cell-division. Fig. 71, 3.20 p.m. ; Fig. 72, 3.25 p.m ; Fig. 73, 3 30 p m. ; Fig. 74, 3.37 p.m. 
