OBSERVATIONS ON UNICELLULAR FORMS 



131 



4. Chlamydomonas alhoviridis (Stein) 



Chlamydomonas Is a small green egg-shaped organism 

 usually less than o.oi mm. In length. It has two or four 

 flagella, a contractile vacuole which appears to open to the 

 exterior at the base of the flagella, and a distinct eye-spot 

 located near the surface In various positions on the side of 

 the body, sometimes nearer the posterior than the anterior 

 end (Fig. 17). In Euglena and Trachelomonas the eye- 

 spot is situated near the contractile vacuole and the base 



-0.03 miii7 



Fig. 17. I. Chlamydomonas alboviridis. II. Chlorogonium, showing struc- 

 ture and form, v, contractile vacuole; 7i, nucleus; ch, chloroplasts; e, eye-spot; 

 mm., projected scale. 



of the flagellum; and It has been suggested that the eye- 

 spot Is nothing more than a collection of w^aste material 

 deposited by this vacuole. In Chlamydomonas It is, how- 

 ever, so far from the contractile vacuole that there does not 

 appear to be any relation between the two structures. 

 These organisms usually swim with the end containing the 

 flagella ahead, but sometimes they swim for short distances 

 with the opposite end foremost. 



I was interested In this form chiefly because it appeared 

 as though its reactions might have some bearing on the 



