MICROSCOPIC OBJECTS. 



Fig. 77. Fructification of the Male Fern (Lastrea Filix- 

 Mas), x25. 



In this drawing the reniform indusium or covering for the 

 sori will be well seen. The sporanges situated under the indu- 

 sium have a small stalk, differing in length according to the 

 species of Fern ; by this they are slightly fixed to the surface 

 of the frond. For their shape &c. when much magnified, see 

 fig. 78. 



On the stipes or stalks of the fronds of Ferns beautiful- 

 shaped scales often occur ; for an example see fig. 26. 



Fig. 78. Spores and Spore-cases of the Brake Fern (Pteris 

 aquilina), x 120. 



This object, as seen under the parabolic reflector, exhibits 

 the sporanges or spore-cases in the act of discharging the 

 spores. Around the outer side of the cases a ring will be 

 noticed, which is called the annulus. This, being very 

 elastic, when the sporange arrives at maturity breaks at a 

 part of the circumference, and by its elasticity ruptures the 

 case, and scatters the spores around. 



Some of these, dropping on a smooth damp surface, grow 

 into a kind of minute leaf, called the prothallus. In this 

 prothallus, at an early period of its growth, appear the repro- 

 ductive organs. The frond is then fertilized, and grows until 

 the sori appear, and when these are ripened the frond dies off. 

 Such, in a few words, is the life and growth of Ferns. 



The sporanges and spores are best mounted in balsam. 



