126 NATURE STUDY 



of great interest to learn how the spores are formed, altho the 

 subject is a rather difficult one to make clear to young children. 

 Reference is made to the formation of the male and female plants, 

 the fertilization of the oospore by the antherozoids, and the 

 development of the sporogonium. 



The Green Scum of Ponds. 



In the many excursions made by the pupils the ever present 

 green scum of ponds and ditches must have attracted their atten- 

 tion and have been the source of manj' questions. 



If a lesson with it goes no further than to show that this 

 slimy mass really is made up of a number of very definite and 

 beautiful forms of plants among which live a large number of 

 interesting animals, it will have accomplished much in extending 

 the view of nature. With a microscope it can supply a never 

 ending train of beauties and wonders. What is given here is but 

 the merest beginning with these objects, one that all can make. 



Have some one bring in a portion of such scum. Place it in 

 a vessel of water, giving it plenty of room to spread out well. 

 Take up a very small portion (too great a portion will give con- 

 fusion onl}') and mount it in water on a glass slip with a cover 

 glass. Allow the children to see it well and make out some of 

 the forms. There will be great interest on the part of the child- 

 ren, but at first very wrong conceptions of what is seen. 



One form of plant is very likely to occur. It consists of a 

 single, long, unbranched thread. Within it are green spiral bands 

 with chlorophyll. The partitions across the plant are the ends of 

 plant cells. The plant consists of a single row of cells. Those 

 who are students of botany will recognize the plant as 

 Spirogyra, of which there are at least forty species in the United 

 States. Of course the children will demand names for the num- 

 erous things which they may chance to see, but few botanists or 

 zoologists could give them all, A frequent examination of pond 



