206 Dynamic T/ieory. 



of cilia, and impregnate the embryo cell, which thereupon germinates, 

 sending roots into the soil and growing above into a fern. The juices 

 of the prothallus furnish nourishment to the Fern till its roots are able 

 to sustain it independently. ( Huxley's Biology.) Thus the Fern 

 represents in its development two forms of reproduction, the first asex- 

 ual by fission, or the repeated subdivision of a single cell, the second 

 sexual, or the reunion of previously differentiated positive and negative, 

 or female and male, cells. Moreover the prothallus is a cellular plant, 

 while the stems of the Fern are vascular, and the fern is the lowest of 

 the vascular plants. The development of the coniomycetes, as above 

 described, appears curiously imitative, in a degenerate sort of way, of 



. that of the Fern. Its pseudospore answers to the spore of the Fern, 

 the promycelium represents the prothallus, the mycelium stands for the 

 roots of the mature Fern, the little spicules may be the remains of an- 

 theridia, and the sporules the impregnated embryonic cells resulting 

 from an internal cryptogamic union of sexual elements. 



Since it is absolutely certain that the fungus is a degenerated organ- 

 ism in the sense of having lost functions, the foregoing coincidences 

 point very suggestively to an ancestry having much in common with 

 the ancestry, of the Bracken Fern. 



The Cystopus, one of the Uredines or rusts mentioned above as a 

 sub-order of Coniomycetes, also has an interesting history. It has two 

 kinds of reproductive organs, Conidia, which are formed in chains on 



- the surface of the plant, bursting through the cuticle, and Oogonia, 

 which are spherical bodies developed on the roots of the mycelium down 

 among the tissues of the plant on which the Cystopus makes its home 

 and its living. These last are called the "resting," or " winterspores, " 

 and are the ones that survive the winter and germinate in the spring, 

 the others being killed. 



When the conidia are placed in water they absorb moisture and swell 

 and the protoplasm inside of them is developed into zoospores, five to 

 eight of them in each conidium, from one end of which they are expelled 

 one by one. At first they remain attached around the mouth of the 

 conidium, but afterwards become free and develop two tails or vibratile 

 cilia, by means of which they swim around in the water like the zoo- 

 spores of algae. The development of these zoospores is accomplished 

 within three hours after the conidium is put into the water. In nature, 

 the water from rains lodging on the leaves in damp and shaded locali- 

 ties causes their germination, aud they go on producing mycelium till 

 stopped by dessication or winter. 



The development of the oogonia produces zoospores in just the same 

 way but in greater number. After their expulsion they enjoy their free- 

 dom in locomotive activity for two or three hours, then their movements 



