454 
Messrs Gardiner and Hill, The Histology 
certain that this function of the connecting threads in ripe endo- 
sperm tissue must be one of only a secondary character. 
We consider, moreover, that there is at the present time, and, 
in the light of existing researches, insufficient ground for laying 
stress on the differences between the pit and wall threads or of 
assigning to either of them any special or distinctive function 
although it is not improbable that some such distinction does 
as a matter of fact exist. 
As to the principle or master function of the connecting threads 
in the endosperm, there can be little doubt that the opinion already 
set forth 1 , and to which Strasburger 2 takes exception, is the true 
view of the case, namely, that the “ connecting threads ” are 
primarily essential for the conduction of food and stimuli during 
the development of the endosperm and the seed, and that in such 
seeds as those of Tamus and Galium the period during which their 
functions are discharged with greatest perfection is “ inter vitam ” 
and not “post mortem .” Endosperms such as that of Phoenix 
rupicola which possess the two forms of threads lend additional 
support to this conclusion, since the wall threads are found in large 
numbers at those parts where they would naturally be most useful, 
for they occur not only in the walls of the peripheral endosperm 
tissue, where they would serve as channels of communication 
between the developing seed and the parent plant, but also in the 
walls of the cells which immediately surround the embryo itself. 
The conclusions to which we are led by a study of the germina- 
tion of the seeds of Tamus and Galium are that although the 
ferments can attack and dissolve the thick cell walls of the endo- 
sperm, without any necessary relation to the “ connecting threads,” 
yet that in the initial stages the penetration of the enzyme may be 
effected by means of the threads, which thus afford a means of 
reaching the internal parts of the wall. 
Secondly, that the connecting threads are concerned mainly 
and primarily with the conduction of food and stimuli from the 
parent plant to the developing embryo and endosperm of the seed, 
and that any further use to which they may be put during the 
germination of the seed must be regarded as only of secondary 
significance. 
1 Gardiner, Proc. Roy. Soc. 1897, p. 107. 
2 Strasburger, loc. cit., p. 536. 
