64 Transactions British Mycological Society. 
Clearly this is not the case. All the seeds were sown on peaty 
soil without controls on sterile media and no proof of any kind 
is offered that the seeds were adequately sterilized. If the soil 
used was from a Calluna station infection evidently could take 
place from roots in such soil, as it may do in nature in the case 
of seedlings germinating near the parent plant. 
The view has never been put forward by me that the endo- 
phyte is not present in soil or that infection cannot take place 
from this source. On the contrary, it is obvious that the soil 
of an area occupied by Calluna will always contain the fungus. 
Concerning the distribution of the endophyte in soil generally 
I have at present no data, nor have I expressed any opinion as 
to its independent occurrence in nature apart from the Calluna 
plant. 
(c) Sterilized seeds in sterilized sotl. 
Seeds were sterilized with 1 °/ mercuric chloride. The soil 
brought from a Calluna area (Diesenhofen) was repeatedly auto- 
claved at 140°C. It is recorded that at the end of five months 
the experimental seedlings were well rooted, the roots being 
entirely free from infection by fungal hyphae. As in the ex- 
periments described under (a), no proof of seed sterility is 
offered. Until such proof can be supplied, it is only possible to 
repeat the criticisms under (a). 
It is greatly to be desired that Dr Christoph should repeat 
these experiments providing rigorous proof of seed coat sterility 
subsequent to sterilization, and that he should then maintain 
his cultures under aseptic conditions. It is not recorded that any 
attempt has been made to do this in the case of those described 
and the possibility of air-borne infection of sterile cultures is 
ignored. It appears to the writer that just conclusions as to 
the biological relationships between organisms found growing 
in close association in nature can only be reached as the result 
of “pure culture” work which will pass the tests demanded by 
any competent bacteriologist. Anything less is obviously un- 
satisfactory and cannot yield conclusive evidence. The following 
quotation from Christoph’s paper shows how far from this ideal 
were the cultures upon which he bases his conclusions: 
“‘Anfangs machten sich einige Zeiten hindurch Rasen von 
Mucor und Citromyces unangenehmen bemerkbar, ohne jedoch 
Schaden unter den Pflanzen anzustiften. Wie bereits anlasslich 
die Beschreibung der Calluna-Steckling Kultur erwahnt wurde 
sind diese Pilze nicht imstande die Wurzeln zu infizieren, weshalb 
ein Nachteil fiir die Sicherheit des Ergebnisses auch nicht zu 
befiirchten war.”’ 
The number of seedlings dealt with is not always mentioned. 
