THE GREEN ALGM 105 



much affinity with Conferva and its alHes (Senn 6^). In the 

 genus C/i/oranm'ba (Bohhn 7), which is the simplest repre- 

 sentative of these Chloromonadinese, we have a naked unicellular 

 motile form, possessed of two cilia of unequal length and 

 capable of amoeboid movement by the protrusion of broad 

 and blunt pseudopodia (sec the first part of this article, fig. i, 

 p, p. 629). Embedded in the protoplasm are from two to 

 six lens-shaped chloroplasts of a yellow-green colour and 

 abundant oil, which is the product of assimilation, while a 

 contractile vacuole is situated beneath the point of attachment 

 of the cilia. The method of reproduction by division has not 

 yet been observed, but resting-cells provided with a thick 

 membrane are formed in response to unfavourable conditions. 

 In Chloramocba we therefore have a Flagellate form agreeing 

 in all essential respects with the zoospores of a Conferva, and 

 a form very like Chloramocba is therefore regarded as being 

 the ancestor of the whole group of the Heterokontae. Another 

 member of the Chloromonadinese, the genus Chlorosaccus of 

 Luther (47), serves as a connecting link between Chloramocba 

 and the algal representatives of the Heterokontae. Chlorosaccus 

 (fig. 4, p) rnay be described as the Tetraspora of the Heterokontan 

 series, although it is still a Flagellate in its characteristics. It 

 is a colonial form appearing in the shape of bright green spheres 

 attached to other water-plants. These spheres consist of soft 

 mucilage, which is composed of pectic substances, and in which 

 green pear-shaped cells with the pointed end directed outwards 

 are embedded at considerable distances. When the cells 

 multiply they divide longitudinally, twice in rapid succession, 

 so that they tend to lie in groups of fours, a feature which 

 heightens the resemblance to a Tetraspora. Each cell contains 

 two yellowish green chloroplasts and a nucleus and contractile 

 vacuole (fig. 4, p), as in Chloramocba. Reproduction is effected 

 by means of zoospores provided with two unequal cilia, which 

 slip out of the enveloping mucilage, and, after a swarming-stage, 

 divide to form new colonies. Resting-cells are formed in the 

 same way as in Chloramocba. 



The Heterokontan series thus shows different types, which 

 are parallel to those found in the Isokontae ; we have noticed 

 the motile unicellular type, the palmelloid type, and the fila- 

 mentous type, but others (like the motionless unicellular type 

 reproducing by zoospores, as seen in Ophiocytium (fig. 4, o), etc.) 



