194 r. KKEBLE AND F. W. GAMBTjE. 



reality an animal cell or part of an animal cell which has 

 associated itself with the green cell, and that the nucleus 

 lying in this colourless part belongs to this animal cell. From 

 the preceding it follows that this suggestion cannot be main- 

 tained ; for the colourless part of the green cell is nothing 

 other than the plug or core of colourless protoplasm which 

 in the free^ active cell occupies the cavity of the cup-sliaped 

 chromatophore, and which in a fluid of osmotic pressure lower 

 than that of sea-^vater becomes displaced excentrically. The 

 question of nucleus we reserve (see p. 196), We turn now to 

 consider the further development of the green cells which, 

 as the result of infection, are planted about in the body. 



The cells increase, sometimes very considerably in size, and 

 undergo division. The process of this division in cells which 

 have not yet become distorted is as follows : The colourless 

 " neck " of protoplasm elongates, extending toward the base 

 of the cell, where come to be placed pyrenoid and eye-spot. 

 A vertical fold appears in the pyrenoid which later cleaves 

 into two. The eye-spot degenerates during the division of 

 the cell, taking on the form of a broken hoop of dull red 

 colour. The ej^e-spot does not reappear in the daughter- 

 cells which arise by longitudinal division. In the case of 

 the larger originally colourless cells the colourless protoplasm 

 occupies the middle of the cell. When about to divide a 

 pyrenoid makes its appearance toward either end of the cell, 

 and what appears to be a transverse division occurs. 



^rhe daughter-cells in either case separate from one another 

 and, lying each in a clear space, undei'go further divisions. 

 These subsequent divisions are, like those which take place 

 in the palmella state, more of the nature of budding than of 

 equal division ; hence are produced rows of cells of gradually 

 decreasing size, which run from the periphery into the 

 deeper tissues of the body (figs. 9 and 10, PL 18), The re- 

 semblance between the green tissue of loosely associated cells 

 Avhich occupies the body of Convoluta and the palmella stage 

 of the alga is noteworthy. 



The appearance presented by an abnormal Convoluta — 



