DIV. I 



THALLOPHYTA 



381 



hyaline form with leucoplasts when cultivated in organic solutions in the dark. 

 Sexual reproduction has been observed by GERTRAUD HAASE in Euglena sanguinea, 



A * B C D 



FIG. 309. Mastigamoeba invertens. A, Free swimming. B, Amoeboid 



i I . 

 (x 666. After LEMMERMAXN.) 



. asgamoea nverens. , ree swmmng. , moeoid condition, (x 1033.) 

 Dimorpha mutans, with retracted (C) and extended (D) pseudopodia. An ingested particle of 

 food is within a vacuole. 666. After LEMHERMAN 



but this requires confirmation. It takes place in the spring at the bottom of the 

 pool, the cells throwing off their flagella and dividing into small amoeboid 

 gametes with one nucleus and two chromatophores ; these gametes then conjugate 

 in pairs. The zygote without undergoing a period 

 of rest then divides into four or eight cells which 

 grow into the normal individuals. 



The numerous colourless Flagellates which have 

 saprophytic or animal-like nutrition must have been 

 derived from those with coloured chromatophores. 

 In some cases near relationship is indicated by 

 agreement in the structure of the cells. 



In the Pantostomatineae particles of food are 

 ingested over the whole surface by means of pseudo- 

 podia (Fig. 309), in the Protomastiginae usually 

 at an oral opening, while two such spots are present 

 in the Distomatineae. To the second group belong 

 certain forms that live in the blood and the gut of 

 animals and give rise to some tropical diseases. 

 Thus Trypanosoma Brucei causes the Tsetse-disease 

 of cattle, and T. gambiense (Fig. 310) the sleeping 

 sickness in man ; both are conveyed by flies belong- 

 ing to the genus Glossina. 



It may be assumed that the Myxomycetes arose 

 from colourless Flagellates and also that the lower 

 Protozoa (Rhizopoda) can be placed in relation to them as a lower group. 



FIG. 310. Trypanosoma gambiense. 

 A, From the blood of an infected 

 monkey, the flagellum forming 

 an undulating membrane. B, 

 From the fly Glo?sina with the 

 flagellum internal. (After 

 MIXCHIN.) 



CLASS IV 

 Myxomyeetes (Slime Fungi) (*> 13 > l4 ' 15 ) 



The Myxomycetes form an independent group of lower Thallophytes; 

 in certain respects they occupy an intermediate position between plants 



