— 15— 



these stages being j^enerally known as generations. The first stage or 

 generation is the small, flat, heart-shaped plant called the prothallium. 

 The second stage is the fern as we know it. The spores are found in 

 numerous groups on the back of the leaves. Each one of these groups 

 is in turn made up of smaller groups which contain the spores. These 

 smaller groups are called sporangia. 



The spores maj' be collected by placing the spore-bearing leaves on 

 sheets of paper, and letting them dry, when the spores will be dis- 

 charged, covering the paper as a fine, brown powder. If these are sown 

 on fine, rather closely-packed earth, and kept moist, and covered with 

 glass so as to prevent evaporation, within a week or two, or longer, a 

 fine green moss-like growth will make its appearance, and by the end 

 five or six weeks, the little flat, heart-shaped plants spoken of before 

 as the first stage appear. They are of a dark green color, and are called 

 prothallia. These prothallia are attached to the ground by fine root- 

 hairs. Very soon we may find growing from the under side of some of 

 the larger of these little plants, the fern as we know it. It is attached 

 to the ground as well as to the prothallium. As the plant grows, the 

 prothallinm dies, leaving the fern as an independent plant, which after- 

 wards bears the spores. 



Note. — The children will not be able to make out the reproductive 

 parts, and it is not necessary for them to do so. They are found on the 

 under side of the prothallium, and correspond to the staminate and pis- 

 tillate parts of flowering plants, but are very diff'erent in form. (The 

 archegonia or pistillate parts are just behind the notch, the staminate 

 parts just back of these. The spermatazoids, which represent the re- 

 productive part of the pollen grains of the flowering plants, are motile 

 and by means of the dew or rain swim to the archegonial cell, which, 

 after fertilization by one of them produces the fern. The fertilized cell' 

 grows directly into the fern, unlike the ovule of the higher plants, which 

 first produces the seed. 



The children, although they need not know about archegonia, etc., 

 will be able to find the groups of spores on the backs of the leaves, their 

 diff'erent methods or arrangement and protection in the various kinds ot 

 ferns. 



Evaporation, Condensation of Vapors, Solution. 



The phenomena of evaporation, condensation of vapors, and of solution, 

 are interesting facts in themselves, and may be made the subjects of 

 many lessons. In addition to the interest the facts possess, knowledge 

 of them allows a better understanding of a number of processes in the 

 life of a plant or an animal, also in the formation of fog, dew, clouds 

 and rain. 



EVAPORATION OF LIQUIDS. 



A few drops each of different liquids may be placed on a clean sheet ot 

 glass, such as glycerine, water, gasoline, alcohol, and ether or chloroform 



