ACTINOMYCETEAE 703 



have begun to disintegrate in large numbers is impaired by tlie presence of 

 large masses of free spores which retain their staining properties for some 

 time after maturing. Later the spore walls seem to become entirely impervious 

 to stains and, as a result, when the secondary mycelium develops, no difficulty 

 is encountered from this source beyond a slight clouding effect. The best 

 results are obtained when the print is made soon after the mycelium begins 

 to adhere readily to the smeared slide. The nature of the killing agent em- 

 ployed was found to have no noticeable effect on the preparation. Flemming's 

 weak and strong, picroformal, picro-acetic, Camoy, and 95% alcohol were tried. 

 To save time in washing, alcohol is most frequently employed. Delafield's 

 hematoxylin, which is the most satisfactory stain, is allowed to act 24 hours 

 and then the preparation is decolorized. Vacuoles, metachromatic and nuclear 

 structures, as well as septa, show clearly. 



Potron & Thiry (1913) recommend the following toluidine blue stains in 

 pus from a case of actinomycosis. The smear is dried, fixed in the flame, 

 cooled. A small amount of the powdered dye is placed on the smear and a 

 drop of water added. After the stain has acted a short time it is rinsed off, 

 and the preparation is dried and mounted in balsam, or the toluidine blue may 

 be rinsed with a solution of 1% eosin in 90% alcohol to partially decolorize, 

 then rinsed in water, dried, and mounted. Or the slide may be left in Lugol 's 

 solution a few minutes before decolorizing with alcoholic eosin. Still another 

 variation consists of partial decoloration with aqueous orange " de Gole." 



This order is composed principally of saprophytes living in soil, more 

 rarely of facultative parasites of plants, e.g., A. scabies on the tubers of the 

 potato (Pig. 118), or parasites on man, where a few species are fairly common 

 and well known, and many have been briefly described with little regard for 

 their morphology and little data regarding their physiology which would en- 

 able them to be recognized when they are again encountered. 



The physiology of this group has been extensively studied for the sapro- 

 phytic species by Lieske (1921), and especially the soil organisms by Waks- 

 man and coworkers during the last decade. 



The systematic position of Actinomyces has long been subject to debate, 

 many of those working with pathogenic species placing them among the 

 pleomorphic bacteria, some, e.g., Lieske (1921), 0rskov (1923), and Jensen 

 (1932), placing them in a separate group intermediate between bacteria and 

 fungi; and mycologists, such as Saccardo, Thaxter, and Drechsler (1919) plac- 

 ing them in the Hyphomycetes. In this connection, it is interesting to note 

 that Lieske states that they are very closely related to Geotrichum candidum 

 (Oidium lacfis), an undoubted member of the Hyphomycetes. Claypole (1913) 

 regarded them as an ancestral type of microorganism, giving rise to yeasts 

 and higher filamentous fungi and to mycobacteria, corynebacteria, and the 

 other bacteria. 



While most authors have kept the majority of the organisms of this group 

 in a single genus, various attempts have been made to erect more or less 



