2 THE FERNS AND 



and pistils ; and as these are generally visible to the naked eye, the 

 whole of this large class of plants is included under the general term 

 of Phanerogams (Gr. phaneros, evident), or plants with conspicuous 

 organs of reproduction. 



But there is another still larger class of plants which have no 

 stamens and pistils, and whose reproductive organs are in many 

 cases so minute that the aid of the microscope is required to bring 

 them to our view. To this class belong Ferns and their allies, 

 Mosses, Mushrooms, Lichens, Seaweeds, and numberless allied forms, 

 and they bear the general name of Cryptogams (Gr. cryptos, concealed), 

 or plants with inconspicuous organs of reproduction. These plants 

 produce, in different parts of their structure, minute reproductive 

 organs termed generally spores. When we shake a dried fern-frond, 

 we frequently shake out a cloud of these in the form of a fine brown 

 dust. If the fresh spores of a fern ai-e placed under suitable conditions 

 of moisture and warmth, they germinate and give rise to a cellular 

 growth, like a miniature seaweed, called a prothallus. This pro- 

 thallus — which, in the case of most ferns, is not more than -rjth to 

 ^th of an inch in diameter — is formed of several cells usually 

 arranged in a more or less plate-like manner. It is furnished with 

 root-hairs, but is without a distinct stem or leaves of any kind. On 

 this miniature and short-lived plant, true sexual organs are produced 

 which, after fertilization, give rise to a second plant — the true fern- 

 plant. All the plants allied to ferns have the same general mode of 

 reproduction, so that in this whole group we notice what is termed 

 an " alternation of generations." The first of these is asexual, the 

 spore giving rise to a prothallus ; the second is truly sexual, and 

 produces a fern-plant similar to that from which the original spore 

 was developed. 



This alternation of generations is a primary distinction between 

 Ferns and Flowering Plants — because though probably it occurs in 

 the latter, stUl it is at such an early stage of the development of 

 the seed, that botanists have not succeeded in fully detecting it. 



Again, from the lower orders of Flowerless Plants, Ferns and 

 their allies are distinguished by many characters which testify to 

 their much higher state of development. The most manifest 

 distinction is that of possessing woody tissue in tlieir stems — this 

 being absent in all the other cryptogams. 



