18 ISOLATION AND CULTIVATION OF FUNGI 



of Barber (1914) is among the early methods employing micro- 

 manipulation. He used a microscope equipped with special 

 mechanical devices to control the movement of capillary pi- 

 pettes by means of which spores suspended in liquids were 

 picked up for transfer. 



Edgerton (1914) also used capillaries attached to the substage 

 to pick up the spores. The upper end of the capillary tube was 

 sealed. Looking through the microscope, the operator lowered 

 the capillary point until it came into contact with the spore in 

 suspension. A drop of ether was then applied to the closed end 

 of the capillary, causing the spore to be drawn up into the 

 capillary. The spore could be expelled subsequently onto the 

 surface of a Petri-dish culture by gently heating the closed end 

 of the capillary. 



The methods employed by Keitt (1915), LaRue (1920), Dunn 

 (1924), and Ezekiel (1930) were basically quite similar. The spores 

 were separated in agar plates by the streak method or the dilution 

 miethod. LaRue then located the spore in the agar or upon its 

 surface by direct microscopic examination. When he had found 

 the spore, he lowered a special marker on the nosepiece to cut 

 out a disk of agar containing the desired spore and then trans- 

 ferred this disk with a flattened needle. Ezekiel located the 

 spore to be isolated by inverting the bottom half of the Petri 

 dish, selected the spore or sporeling, and with India ink marked 

 its position on the bottom of the dish. The dish was next righted, 

 and a disk of ag^ar immediately above the marked area was cut 

 out and removed. If the dot of ink is placed while the operator 

 is looking through the microscope, it can be accurately located. 

 This method has much to commend it, especially if spores are 

 well spaced and if it is desired to make numerous isolations. 



Brown (1924) employed a mechanical appliance to bring a 

 capillar)^ tube near the hyphal tips in a colony arising from 

 germination of a well-isolated spore. The tips were then drawn 

 into the capillary and expelled upon another plate. After a day 

 or two on the new medium the tips were well spaced, and a 

 single hyphal tip could be cut off. 



Hanna (1924), in isolating single spores of Hymenomycetes, 

 placed a generous fragment of the hymenial surface on a sterile 

 microscopic slide, permitting the basidiospores to be discharged. 

 After discharge, and during observation through the microscope, 



