41 6 Wilson. — Spermatogenesis in the Bryophyta. 
and Targionia. Thuret also noted that the mother-cells of the spermatozoids 
of Fossombronia and Targionia were discoid in shape with one convex and 
one plane surface, and that they were often united together in pairs by their 
plane surfaces. In Funaria hygrometrica he described the polygonal 
mother-cells, each of which gives rise to one spermatozoid. He also described 
and figured the monoecious habit of this plant, an account of which has been 
recently given by Boodle (14). 
Schacht (51) in 1852 found in Pellia epiphylla that the nucleus of the 
spermatogenetic cells becomes smaller and elongated, and finally forms the 
body of the spermatozoid. Later (52), after the examination of a number 
of different plants, he concluded that the nucleus takes some part in the 
formation of the spermatozoid, but that it usually disappears in consequence. 
There is a complete protoplasmic covering around the body of the spermato- 
zoid, and at the posterior end this is enlarged to form the vesicle ; the cilia 
are also protoplasmic outgrowths. 
Kny (38) in 1867 described the ‘tesseralen Zellen i. e. the rectangular 
cells, in the developing antheridium of the Ricciaceae, and concluded that 
each of these gave rise to one spermatid. 
The disappearance of the nucleus was also described by Strasburger (61) 
in M av chan tia poly morpha. Each spermatozoid mother-cell at first possesses 
a distinct nucleus, but during development this gradually breaks up, leaving 
the mother-cell filled with homogeneous contents. The spermatozoid is 
formed from a band-like thickening which appears later on the upper side 
of the cell. Sachs (50) gives a similar account of the development in 
Nitella. On the other hand, Schmitz (56) found that the nucleus did not 
disappear in the Characeae and Musci. The body of the spermatozoid 
is formed by the thickening and elongation of the outer parts of the nucleus, 
while the inner portion gives rise to the vesicle ; only the cilia have a proto- 
plasmic origin. 
The opinion that the body of the spermatozoid was of nuclear origin 
was confirmed by the chemical investigations of Zacharias (77) in 1881. 
He showed that in the Characeae and Musci the nucleus of the mother-cell 
and the body of the spermatozoid agree in their reactions when treated with 
various substances. From these investigations he concluded that the body 
of the spermatozoid is formed from the nucleus, the protoplasm giving rise 
to the thin skin surrounding the body, the cilia, and the vesicle. 
The production of two spermatozoids by the division of each of the 
rectangular cells of the antheridium was first noted in Pellia by Goebel (25) 
in his article on the Muscineae in Schenk’s Handbuch, but in the remaining 
Hepaticae he states that one spermatozoid is formed in each mother-cell. 1 
The nucleus does not disappear, but produces the spermatozoid directly ; 
its peripheral layer thickens, and this by splitting gives rise to the body, whilst 
1 p- 34 2 * 
