CLASSIFICATION OF PLANTS. 13 



current of water and spread over the slide, forming delicate 

 threads in which most active streaming movements of the cen- 

 tral granular protoplasm may be seen under the microscope, 

 and the ends of the branches may be seen to push forward 

 much as we saw in the amoeba. In order that the experiment 

 may be successful, the whole apparatus should be carefully 

 protected from the light, and allowed to stand for several 

 hours. This power of movement, as well as the power to take 

 in solid food, are eminently animal characteristics, though the 

 former is common to many plants as well. 



After a longer or shorter time the mass of protoplasm con- 

 tracts and gathers into little heaps, each of which develops into 

 a structure that has no resemblance to any animal, but would 

 be at once placed with plants. In one common form (Trichia) 

 these are round or pear-shaped bodies of a yellow color, and 

 about as big as a pin head (Fig. 5, /)), occurring in groups 

 on rotten logs in damp woods. Others are stalked (Arcyria, 

 /Stemonitis) (Fig. 5, J, K), and of various colors, red, brown, 

 etc. The outer part of the structure is a more or less firm 

 wall, which breaks when ripe, discharging a powdery mass, 

 mixed in most forms with very fine fibres. 



When strongly magnified the fine dust is found to be made up of in- 

 numerable small cells with thick walls, marked with ridges or processes 

 which differ much in different species. The fibres also differ much in 

 different genera. Sometimes they are simple, hair-like threads ; in 

 others they are hollow tubes with spiral thickenings, often very regu- 

 larly placed, running around their walls. 



The spores may sometimes be made to germinate by placing them in 

 a drop of water, and allowing them to remain in a warm place for about 

 twenty-four hours. If the experiment has been successful, at the end of 

 this time the spore membrane will have burst, and the contents escaped 

 in the form of a naked mass of protoplasm (Zoospore) with a nucleus, 

 and often showing a vacuole (Fig. 5, -u), that alternately becomes much 

 distended, and then disappears entirely. On first escaping it is usually 

 provided with a long, whip-like filament of protoplasm, which is in active 

 movement, and by means of which the cell swims actively through the 

 water (Fig. 5, / 1). Sometimes such a cell will be seen to divide into two, 



