420 Bulletin 315 



The brief history already given differs decidedly from that which fol- 

 lows, as a casual comparison will readily show. We note at once, 

 in the consideration of the earher history, that isolation was concerned 

 with all fungi which might arise. The investigations that are now to be 

 noted are limited to particular groups or species only, depending on 

 whether the work is concerned with saprophytes or with facultative 

 parasites. 



Among the first to receive mention should be Butler ('07), to whom 

 much credit is due for his excellent treatise on the genus Pythium. Al- 

 though he does not deal with soil forms alone, yet his work must constitute 

 a valuable part of the history that we are discussing, because of 

 the species he has unquestionably shown to be soil organisms as 

 well as the new method of isolation evolved by him. We can do 

 no better than use the author's own words in the description of his 

 method: 



Garden earth, preferably from the neighborhood of the roots of higher plants, 

 is taken three to six inches below the surface of the soil and placed in a large shallow 

 vessel to which enough tap water is added to leave a layer free above the earth. In 

 this the substratum is floated. Numerous trials have shown that the nature of the latter 

 is by no means a matter of indifference. . . . By far the best medium which I 

 have found for general use is boiled sliced root of Abutilon, either plain or steeped in 



decoction of flies Working in the tropics I have found it very useful to 



acidify slightly with citric acid the water used during the first step in the isolation from 

 earth, in order to keep down bacteria. The acid often, however, interferes with spore 

 formation, so that it is necessary to shorten the time as much as possible. After twenty- 

 four hours, the culture substratum is removed and placed in a relatively large quantity 

 of water, and after another twenty-four hours examined. 



From a consideration of the above we are again forcibly reminded that 

 there is considerable specialization as to food relations, and so forth, 

 amongst soil organisms, and that different methods and media yield 

 decidedly different results. 



The species isolated by Butler are Pythium de Baryanum Hesse, P. 

 intermedium de Bary, P. vexans de Bary, P. proliferum de Bary, P. 

 rostratum Butler, P. monospermum Pringsh. 



Following Butler are Hagem, Lendner, and Namyslowski. All three 

 have confined their isolations to the Mucorales and many new species 

 have been found. As a result of the work of the first two, especially, the 

 demand has arisen for a new monograph of the order. This demand is 

 supplied by Lendner's " Les Mucorinees de la Suisse," 1908. But even 

 since that date these investigators have still isolated many new species, 

 so that the monograph is now somewhat incomplete in that about nine 

 new species are not considered within its pages. 



('07) Butler, E. J. An Account of the Genus Pythium and Some Chytridiaceae. 

 Mem. Dept. Agr. India, Bot. Ser. No. 5. i: 1-160. pi. 10. 1907. 



