960 



SCIENCE 



[N. S. Vol. XXVII. No. 703 



sis of the merits of the case. The three 

 grounds assigned evade the real issue of my 

 views which was privately stated by the presi- 

 dent to be the basis of his action. And this 

 real issue, which is not frankly stated, but set 

 aside by the interposition of an unjustifiable 

 personal attack, is a violation of the principle 

 of Lehrfreiheii. 



H. Heath Bawden 



Jniveesitt of Cincinnati, 

 May 31, 1908 



SPECIAL ARTICLES 



A METHOD OF SENDING PURE CULTURES OF FUNGI 



For several years the writer has had occa- 

 sion to receive cultures of moulds from dif- 

 ferent parts of this country and from abroad 

 and has learned to expect a large percentage 

 of contaminations even when the cultures are 

 pure when shipped. The usual method is to 

 send a pure culture of the mould in a fresh 

 slant tube of nutrient which has been 

 hardened with either gelatin or agar. During 

 transit the nutrient generally becomes shaken 

 up against the cotton plug and there results 

 an infection of bacteria or of moulds like 

 PenicilUum and Aspergillus^ the spores of 

 which are usually present on the outside of 

 the cotton plugs but which germinate and 

 grow down into the tubes when the plugs are 

 wet or the surrounding air is rendered moist 

 by rubber caps or even by paper wrappings 

 which more or less completely seal the tubes. 

 Eecently the writer received a shipment of a 

 considerable number of tubes from Utrecht, 

 Holland, from the fungus collection of the 

 Association Internationale des Botanistes. 

 They were apparently fresh cultures and a 

 very large proportion were thus irredeemable 

 from contamination with weed fungi. It 

 seems not undesirable, therefore, to describe in 

 some detail a method of shipping cultures 

 which experience has shown to be free from 

 the objectionable features already mentioned, 

 although it is a method which might naturally 

 occur to any one having spores to send. 



If cultures are to be sent in test-tubes it 

 is advisable to avoid gelatin and to use rather 

 stiffer agar than usual, which should be allowed 

 to dry out and thus fasten itself against the 



sides of the tubes before packing. For stock 

 cultures, which are to be kept a year or so, the 

 writer has successfully used as much as 30 

 and even 35 grams of agar to the liter, and 

 agar of this degree of hardness might be used 

 for shipping. While with proper precautions 

 pure cultures may be sent in test-tubes yet 

 the possibility of breakage or of infection 

 already pointed out, as well as the possible in- 

 convenience of custom-house inspection when 

 packages are received from foreign cor- 

 respondents, are objections to this method. 



These disadvantages have led the writer to 

 use small paper envelopes such as are made 

 by druggists in putting up powders or by 

 botanists in preserving fungi in exsiccati. 

 A mass of the fungus filaments containing 

 spores are taken with a sterilized instrument 

 from a pure culture of the species desired, 

 together with some of the substratum, and put 

 into the envelopes, where it is allowed to dry. 

 Several of these culture envelopes may be sent 

 with little inconvenience in an ordinary letter. 

 It has been the writer's practise as a matter 

 of precaution to sterilize the envelopes either 

 in an autoclav or in a dry oven at 140° C. 

 before using them. The danger of infection 

 is probably not very great if the culture en- 

 velopes, although unsterilized, are made up of 

 clean paper that has not been unduly exposed 

 to contamination since the few spores of Peni- 

 cilUum or other fungus weeds that may be 

 present have little opportunity of germinating 

 and spreading if the material used in the 

 transfer be rapidly dried and kept in a dry 

 condition. In making up the dry cultures it 

 seems desirable to include some of the sub- 

 stratum mixed with the spores. In this way 

 even such bacteria as Bacillus prodigiosus have 

 been successfully sent through the mail and 

 moulds have been received in good condition 

 from as distant countries as the Philippines. 

 Naturally with those fungi that fail to fruit 

 well in captivity and to form spores or other 

 reproductive bodies which retain their vitality, 

 recourse must be had to test-tube cultures with 

 hard agar. The envelope method has been 

 used for several years by the writer and by 

 several of his correspondents, and for the 

 forms most generally cultivated seems to meet 



