256 MONADS CHAP. 



contractile vacuole, and performs both euglenoid and 

 ciliary movements. 



In both these organisms we evidently have conflicting 

 characters : the cellulose wall and holophytic nutrition 

 would place them both among plants, while from the 

 contractile vacuole and active movements of both genera, 

 and from the holozoic nutrition of Euglena, we should 

 group them with animals. That the difficulty is by no 

 means easily overcome may be seen from the fact that 

 both genera are claimed at the present day by zoologists 

 and by botanists. 



Another mode of nutrition, which under certain cir- 

 cumstances may also be adopted by E'uglena. occurs 



c.vac 



FIG. 70. A Monad (Heteromita rostrata), showing nucleus (nu), contractile vacuole 

 (c. vac), and two flagella (ffl, /T 2 ). (x about 1500). (From Parker's Biology. 

 after Dallinger.) 



in certain organisms which must now be referred to 

 very briefly. 



When animal or vegetable matter is placed in water 

 and allowed to stand at the ordinary temperature, the 

 well-known process of decomposition or putrefaction 

 (pp. ii, 152, and 237) sooner or later sets in, the water 

 becoming turbid and acquiring a bad smell A drop of 

 it examined under the microscope is then found to teem 

 with very minute unicellular organisms, some of which 

 are known as Monads, much smaller than Euglena, the 

 form represented in Fig. 70 (Heteromita) being only 



