Mycorrhiza in the Evicaceae. M. Cheveley Rayner. 63 
As a further result of experimental work I claim also to have 
shown that infection of the seeds within the fruits takes place 
as a consequence of the widespread distribution of the endophyte 
throughout the plant body. The evidence for this need not be 
discussed here, but it may be pointed out that the production 
of infected roots by ‘“‘cuttings” rooted in sterilized sand under 
aseptic conditions would provide convincing confirmation of the 
presence of the fungus in the shoot tissues. 
To pass to Christoph’s work on seed cultures. The behaviour 
of seeds and seedlings was investigated as follows: 
(a) Unsterilized seeds on sterilized soil. 
Seeds were subjected to prolonged soaking in rain water and 
sown on peat (Torfmulle) sterilized by repeated autoclaving: 
controls were sown on untreated peat. 
After six months it is recorded that the seed sown on sterile 
peat had produced seedlings 7-11 mm. high with root systems 
24mm. long in all cases entirely free from fungus infection. 
Other cultures of a similar kind gave on unsterilized soil, 
seedlings with roots infected: on sterilized soil, seedlings equally 
vigorous with roots which were still entirely free from fungal 
infection a year after sowing. 
With regard to these results it may be pointed out that until 
my claim of seed coat infection has been disproved, all seedlings 
raised from unsterilized seed would be assumed liable to in- 
fection at germination. In my own researches, I have been 
careful to use seed from as many different sources as possible, 
but have never observed a case of non-infection of roots 
in experimental plants, nor have I ever found a plant growing 
under natural conditions or under cultivation without mycor- 
thiza. I do not deny the possibility that such plants may 
exist; I can only affirm my own experience in this matter. On 
the other hand, it is not always easy to observe infection in the 
clean roots of seedlings and in the absence of opportunity to 
examine the material, it is only possible to assume that the 
presence of mycelium in the roots of these seedlings has been 
overlooked by Christoph. 
(b) Sterilized seeds on unsterilized soul. 
Seeds were sterilized in various ways: in the later experiments 
by means of 1 % mercuric chloride. After sterilization they 
were sown on a suitable soil from a Calluna area (Diesenhofenen 
Erde). These cultures are recorded as giving after six weeks 
seedlings 5-10 mm. high with roots normally infected. Christoph 
assumes that these experiments provide conclusive proof that 
infection by the mycorrhizal fungus takes place only from soil. 
