1914] 
SCHRAMM—PURE CULTURE METHODS IN THE ALGJE 25 
subject, or which outline in detail the methods employed. 
Beyerinek, in 1890 (4, 6), appears to have been the first to 
succeed in isolating species of alge in pure culture. Ditch 
water, boiled with ten per cent gelatin, and cooled, was mixed 
with a drop of water rich in protococcoid alge, poured into 
dishes, and allowed to cool. Numerous minute algal colonies 
appeared in course of time, and the number of bacterial colonies 
developing was so small that successful transfers of Scenedesmus 
acutus Meyen and Chlorella vulgaris Bey., were made, both 
organisms being subsequently cultured on a variety of media. 
In addition, the gonidia of Physcia parietina were obtained 
pure. Small pieces of the lichen thallus, carefully washed, 
were placed on solid gelatin plates. Those which showed 
themselves to be free from foreign organisms were transferred 
to gelatin plates containing malt-extract, the fragment being 
first torn to bits with needles and then dragged over the sterile 
surface. In a few days, small colonies of the algal symbiont 
appeared from which successful transfers were made. Іп a 
later paper (5), Beyerinck adds Stichococcus major and a second 
species of Chlorella to the list of alge previously cultured in 
a state of purity, the technique, in general, being the same. 
Miquel (16) was the first to isolate а diatom in pure culture. 
Subsequently, Richter (20, 21) isolated Nitzschia Palea (Kütz.) 
W. Sm., and Navicula minuscula Grun., by the use of synthetic 
agar plates. Attention is called by this author to the impor- 
tance of using agar which has previously been washed to free 
it from soluble impurities. A mixture of diatoms and other 
algee was placed on the surface of washed agar plates, and from 
the impure diatom colonies which developed transfers were 
made to other plates until at length pure cultures were obtained. 
In his isolations of certain protozoa in pure culture, Ogata 
(18) also obtained Polytoma uvella. While his method seems 
unnecessarily complex, it is of interest here. Sterile capillary 
tubes were filled in part with а column of sterile water, and 
subsequently а column containing the organisms was added 
below, care being taken not to separate the two by air. Both 
ends of the tube were then sealed. After sufficient time had 
elapsed for the movement of the motile Polytoma cells from the 
lower column into the upper sterile one, the tube was broken in 
