EQUISETINE^. 
393 
for a few days), show, when sown in water or on damp soil, the preparatory 
phases of germination after a few hours. In the course of some days the pro- 
thallium becomes developed into a multicellular plate, the further growth of which 
then proceeds very slowly. The spore, which contains a nucleus and chlorophyll- 
granules, increases in size as soon as germination commences, becomes pear-shaped, 
and divides into two cells, one of which is smaller with scarcely any except colourless 
contents, and soon developes into a long hyaline 
root-hair (Fig. 274, /, //, ///, w), while the 
anterior and larger cell includes all the chloro- 
phyll-granules of the spore which multiply by 
division. This cell produces by further divisions 
the primary plate of the prothallium, which in- 
creases by apical growth and soon branches 
[III-VI). The process of multiplication of the 
cells is therefore apparently extremely irregular ; 
even the very first divisions vary ; sometimes 
the first wall in the primary apical cell which 
contains chlorophyll is but little inclined with 
respect to the longitudinal axis of the young plant 
(in E. Telmateia it sometimes coincides with it) ; 
in other cases, on the contrary, this cell developes 
into a longish tube, the apical part of v/hich is 
cut off by a transverse septum (occasionally in 
E. arvense). The further growth is brought about 
by one or more apical cells dividing by trans- 
verse septa, and longitudinal walls are subse- 
quently formed in the segments in an order very 
difficult to determine. Ramification takes place 
by the bulging out of lateral cells, which then 
continue their growth in a similar manner. The 
chlorophyll-granules in the cells also increase con- 
tinuously by division. The young prothallia are, 
in E. Jelmaieia, usually narrow and ligulate, and 
consist of but a single layer of cells. The older 
prothallia are, both in this and in other species, 
branched in an irregularly lobed manner ; one of 
the lobes takes, sooner or later, the lead in growth, becomes thicker and fleshy, 
consisting of several layers of cells, and puts forth root-hairs from its under side. 
The prothallia of the Equisetacese are, in general, dioecious. The male pro- 
thallia remain smaller, attaining a length of a few millimetres, and produce archegonia 
only in exceptional cases on shoots of later origin (Hofmeister). The female 
der Wurzeln (Beitr. zur wissen. Bot. von Nägeli, Heft IV. München iSö;). — Pfitzer, lieber die 
Schutzscheide (Jahrb. für wissen. Bot. vol. VI. p. 297). — Russow, Vergl. Unters, über die Leit- 
bündelkrypt. Petersburg 1872, p. 41. — Janczewski, über die Archegonien, Bot. Zeit. 1872, p 420. 
Van Tieghem, on the roots, in Ann. des sei. nat fth series, vol. XIII, — [Sadebeck, Ueb. die Entwicke- 
lung der Prothallien der Schachtelhalme, Bot. Zeit. 1877.] 
protha liuni of Equisetum Tehiiateia ; w the first 
root-hair; t ruiiment of the prothalhum. Tlie 
order of development follows the numbers /—^^7 
(X about 220). 
