Kusano, Further Studies on Aefjinet/la imlica. 
297 
Pollia, Zlngiher and Canrui, most of them being already known 
as natural bosts ^). Again the development of the tubercles was 
not only very unequal on tbese plants, but even in the same 
species it was different on different individuals. After two weeks 
all the seedlings reached the stage shown in Fig. 4, but the size 
of the tubercles during the next two weeks was very variable, 
some attaining to the size of poppy grains and others to that of 
the corn. The growth of the tubercles were especially vigorous 
on Zflnyibei' and Pollia. It was also observed that the development 
of the parasite was less rapid on pot-plants than on those in the 
field: in September it was all in flower in the field while the 
shoots scarcely appeared above ground in the pots. It foUows 
that the growth of the parasite is most intimately connected with 
that of the host, and in particular with the activity of its roots. 
I have already remarked that the host-root induces no ger- 
mination when too feebly developed. The same cause must not 
be assigned for the nondevelopment of tubercles on some of the 
plants used in the experiment. Forinstance, Allium, Iris, Accrrus, 
Hemerocallis, and others produced numerous vigorous rootlets and 
appeared always to be much more rapid in growth than some 
natural hosts such as Carex and Miscsanthus. It is certain, there- 
fore, that there are fit and unfit plants as the host of Aeginetki. 
As for the intimate relation between the seedlings and the 
proper hosts, or plants unfit as the host, I have no evidence to 
bring forward. It may be that the roots of some plants are unfit 
for inducing the formation of the primary haustorium, the hair- 
tendrils, or perhaps the tubercles. Which of these assumptions 
holds true must be settled by further investigations. At present 
I can go no farther than to state that the Stimulus which 
causes the seeds to germinate and the Stimulus which 
causes the seedlings to develop further are of a quite 
different nature. 
General Remarks and Summary. 
On looking over what have been described above, we see 
that Aeginetia presents many remarkable characters which must 
be due to its parasitic life. In the first place, the formation of 
the hair-tendrils is a most specialised contrivance for finding out 
the host. It may be that in Lathraea. and Orobanche the seedlings 
can not easily reach the host, unless the seeds are placed dose to 
the host-root so that their radicles lie against the latter. Other- 
wise, the tip of the radicles may diverge from the host-root more 
and more as they grow further and fuiffher so as to make the 
development of the seedlings impossible, just as the same organ 
of Visciun would do if it should be insensitive to light, or the 
same organ of autophytic plants if insensitive to light and gravity. 
9 See foot-note in the preceding page. 
