s* 
MR. E. J, LOWE ON SCOLOPENDRIUM VULGARE. 531 
On October 15th, 1893, one of the split prothalli threw upa 
frondlet, how impregnated it was then impossible to say, but a 
skipjack (Podura plumbea) was noticed under the bell-glass, 
it might have been there for some time, for the plants had not 
been examined for three weeks, owing to my illness. A 
portion of the prothallus containing this frondlet was severed 
from the rest of the prothallus, and grew rapidly, the 
remainder also grew healthily. Subsequently an experiment 
was made with a skipjack, portions of prothalli (53 years old) 
were planted in a pan and covered with an inverted wine- 
glass, these had only archegonia, but outside this glass portions 
having only antheridia were planted, and the whole covered 
with a large bell-glass; skipjacks were introduced in the 
outer portion, and left there for a few days: then the wine- 
glass was removed, and the skipjacks had access to the portions 
having archegonia; the insects were removed in 24 hours, and 
in 14 days afterwards frondlets appeared, but they were 
certainly two or three days old when detected, therefore the 
period from impregnation to frond-life was probably only 
12 days. At the same time, in a second pan, portions bearing 
male, and portions bearing female organs were planted half an 
inch apart, but, although under the same bell-glass, after three 
months they had produced no frond-life. 
The special experiment which is to be described is the 
repeated division of one portion of a prothallus in order to 
remove every portion of the original prothallus. 
In the divided prothalli it is necessary to point out that 
the archegonia are assumed to be on the upper half, and that 
in dividing them, the sexes are kept on different portions. i 
know that it is said that archegonia and antheridia are some- 
times found together, but in the large number of experiments 
that I have made on the assumption that they are far apart, I 
have not had an instance of frond-life occurring until an upper 
and a lower portion has been brought together, and there has 
never been an instance, after bringing them together, of a 
failure to produce frond-life. 
In repeating these divisions of the same divided prothalh, 1% 
is evident that from the new growth of the prothalli in each 
division the original prothalli becomes further and further 
removed from the portion where the archegonia were situated 
until it is possible to cut off a portion that has no part of the 
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