BRIEFPER ARTICLES, 
THE MITOSES IN THE SPORE MOTHER-CELL OF 
PALLAVICINIA. 
(WITH SIX FIGURES) 
In 1894 Farmer published a paper? on Pallavicinia decipiens report- 
ing the occurrence of very peculiar phenomena in the division of the 
spore mother-cell. According to his account the nucleus in preparation 
for division is surrounded by dense protoplasm which projects into 
each of the four lobes of the mother-cell and forms a four-rayed star. 
He termed this structure a “quadripolar spindle.” After the formation 
of the ‘quadripolar spindle,” four chromatic droplets make their 
appearance in the nucleus as the first positive evidence of approaching 
division. The four chromatic droplets become four chromosomes, 
which by division are doubled in number. The resulting eight rod-. 
shaped chromosomes point off in pairs towards the four lobes of the 
spore mother-cell.. Further doubling takes place, increasing the total 
number of chromosomes to sixteen, and four chromosomes pass simul- 
taneously to each pole of the four-rayed spindle, which persists to the 
end. 
Farmer’s later studies? on other Jungermanniales revealed the 
presence of the “quadripolar spindle” in the early stages of mitosis, 
but in no case did he find a repetition of the peculiar conditions 
described for Pallavicinia. In all other forms the “‘quadripolar spin- 
dle” is a temporary structure, which is later replaced by normal 
bipolar spindles of two successive mitoses with longer or shorter inter- 
vals between. Farmer interprets the temporary four-rayed star of 
these plants as transitional between the ‘“quadripolar spindle” of 
Pallavicinia and the normal bipolar spindle. 
Davis in r901 described? conditions during spindle formation in 
the spore mother-cell of Pe//a epiphylla substantially in agreement 
*FARMER, Studies in Hepaticae: On Pallavicinia décipiens Mitten. Ann. Botany 
8:35. 1894. 
?FaRMER, On spore formation and nuclear division in the Hepaticae. Ann. 
Botany g: 363 and 469. 1895. 
3Davis, Nuclear studies on Pellia. Ann. Botany 15:147. 1901. 
384 [NOVEMBER 
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