. Botany for high schools and colleges. Botany. 42 BOTANY. protoiVasm of the mother-cell is used. The former he calls Free-Cell Formation,,Sii\{i the latter Formation of Cells by Division of the Mother- Cell, and includes also under the last a part of what has been described above under the head of Fission. It is doubtful, however, whether such a division is of much importance. (&) What has been called the Rejuvenescence of a cell may be mentioned here. The phenomena connected with it are as follows: The proto- plasm of a cell contracts, ex- pels a portion of the water contained in it, and
. Botany for high schools and colleges. Botany. 42 BOTANY. protoiVasm of the mother-cell is used. The former he calls Free-Cell Formation,,Sii\{i the latter Formation of Cells by Division of the Mother- Cell, and includes also under the last a part of what has been described above under the head of Fission. It is doubtful, however, whether such a division is of much importance. (&) What has been called the Rejuvenescence of a cell may be mentioned here. The phenomena connected with it are as follows: The proto- plasm of a cell contracts, ex- pels a portion of the water contained in it, and escapes through a slit in its wall ; ihe naked mass becomes for a time a free-swimming zoos- pore, after which it secretes a wall of cellulose, and begins to grow and form new cl41s by fission. Cases of this kind occur in CEdogonium, Stigeo- clonium, and many other aquatic Thallophytes. An interesting fact, but proba- bly of no great significance, is that the axis of growth of the new. cell is perpendicular to that of the old one. While there can be no doubt that this process, as Sachs .1, vertical section ^^^sists,* "must be regarded of The whole plant; /i, the layer morphologically as the for- inwhi'h the spore-forming sac!« lie , <S. the tissue ,^^.- „ ^^ „ „^ , „ n 5)+i „„„ of the fungus envelopng the hynienium at its mation of a new cell, there edge ^ in a cup like manner ; at the base of tlie can be little question that it tissue S fine threads arise, which grow between . , , ^ j. ^ ^ ^\ ^ the particles of earth, i?, a small portion of the ^s Closely related to the forma- hymenium;.9;i, sub-hymenialLiyer of densely in- tion of zoospores described terwoven filaments (hyphse) ; a to/, spore-form- /^ ing sacs («.<fa), with thin filaments (piraphyses) above (p. 4U). ihe dilier-; between them. Ax-20,Bx Sachs. ^^^^ jg ^j^^t in the formation of ordinary zoospores the mother-cell breaks up into more tha
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