42 MANUAL OF ZOOLOGY sect. 



solved form from the substances in the infusion. Others, 

 living in internal cavities of the bodies of higher animals, 

 receive, in a similar way, nourishment from the juices of the 

 animal they infest. Organisms, whether plants or animals, 

 which receive their nourishment in the former of these two 

 ways, are said to be saprophytic as regards their nutrition, 

 while such as obtain it from other living organisms are said 

 to be parasitic. But a large proportion of the Mastigophora 

 are neither saprophytes nor parasites, and are nourished in 

 one of two other ways, or in both of them. Many take in 

 minute solid particles of organic matter, usually in the form 

 of minute living organisms. In many such cases, there is, 

 as in Euglena, an aperture, the mouth, opening into a short 

 passage, the gullet, by which the food is received into the 

 protoplasm in the interior of the body ; but this is not 

 always present, and in such cases (Fig. 13, 8) the food-parti- 

 cles are taken in by a process not unlike that which we have 

 seen to occur in Amceba. But, on the other hand, many of 

 the Mastigophora are not distinguishable from plants by their 

 mode of nutrition ; and on that ground, taken in connection 

 with their structure, which is in nearly all respects that of 

 a typical unicellular plant, have almost equal claims to be 

 ranked in either the vegetable or the animal kingdom. 

 They have a cell-wall of cellulose like a plant cell, they 

 contain chlorophyll or a red colouring matter, kamato chrome, 

 of similar composition, and they have no mouth. They 

 must, therefore, be nourished precisely after the manner 

 of a green plant, and, if they are assigned to the animal 

 kingdom instead of to the vegetable, it can only be because 

 the possession of flagella seems to ally them with forms that 

 are of undoubted animal character. 



Colonies are of frequent occurrence among the Mastigo- 

 phora. Sometimes there is a branching slender stalk 



