210 Dynamic Theory. 



ing a tube connecting the two cavities. The fluids from the two cells 

 meet and mix in the tube and form the spores. The old cells then drop 

 off, leaving the spore tube or sporangium, as it is called, to mature and 

 discharge the spores. This recalls the performance of the Ascomycetes 

 in the production of the zygospores. Some species of Desmids and 

 Diatoms produce spores without the conjugation of two individuals. 

 They may be called hermaphrodites. The protoplasm of a single 

 individual becomes granulated and turns to spores, which, from their 

 active and restless movements in the cell and after they burst it open 

 and escape, are called zoospores. In some cases cilia are developed from 

 their shells, which have a forward and backward movement like micro- 

 scopic oars, by which they move in various directions and spin around. 

 They pause from apparent exhaustion, rest, and begin again. 



They recall the zoospores of numerous fungi mentioned above. 

 Where there is reproduction by both fission and spores, the latter, 

 may be regarded as specially differentiated organs in which the neces- 

 sary morphology and arrangement of molecules for going on is com- 

 pleted, but the function of which is arrested, to be renewed at a 

 future time, while the former fission is to be regarded as simply the 

 continuous growth of the same individual. An}' organism grows by the 

 continued segmentation or fission of the cells composing it, provided the 

 cells remain attached to each other after the division. A man's hand is 

 larger than a child's because the cells, after their repeated fission, 

 remain together under the same roof of skin. In the case of* the Des- 

 mid or Protococcus, the two or four pieces of cell after fission grow to 

 maturity of size and shape, but instead of remaining together to form a 

 compound organism, fly apart to remain simple. The cells that result 

 from fission in those organisms that have the spores also, may therefore 

 not be able to renew the growth of the organism after it has once been 

 stopped. They are to be compared with the cells in the leaf of a 

 deciduous tree, that keep on subdividing and multiplying all summer, 

 but die in the fall, and they recall the summer growth and production 

 of summer mycelium and summer spores in the conidia, of the C} T stopus, 

 and other Uredines as related above. And the zoospores of the Desmid 

 are to be compared with the "resting," or ''winter spores," of cysto- 

 pus the products of the oogonia and equivalent to the seeds of the 

 higher organisms. In those species of the Protococcus, Diatom and 

 Desmid among the algae, and the Torulse among the fungi, that never 

 have any spores, no differentiation of reproductive functions and organs 

 has taken place. The one cell contains the possibility of continuous 

 growth by repeated division as long as the conditions of such growth 

 endure, and on the termination of such conditions, the vital energy 

 barred and deflected from going forward in ordinary growth is brought 



