August 25, 1922] 



SCIENCE 



227 



bodies which are formed abundantly on certain 

 media. From these pure cultures were made 

 and subcultures have been carried on through 

 sixteen consecutive non-sexual generations, both 

 by the single spore method and by ordinary 

 transfers from one tube to another, without any 

 variation in the appearance or nature of this 

 strain. The mycelium in mass is a true albino 

 or may at times take on a light flesh color. 



Throughout an intensive study in culture 

 covering thirty months' time, and employing 

 every variation in condition that could be 

 thought of as an influencing factor, there has 

 been no ascus or sexual stage developed either 

 in the normal or albino strain. With these 

 facts in mind, it would seem that the phenom- 

 enon here reported can only be referred to some 

 sudden change which occurred in the mycelium 

 or eonidia of the normal strain, and in any ease 

 has no connection with any sexual process. 



The abruptness of this change, and the con- 

 tinual difference shown by contrasting cultures 

 of the albino and the normal strain, is very 

 striking. This change does not seem to fall 

 into that class of somatic mutations so far re- 

 ported in fungi which are usually described as 

 a dwarfing or reduction of the development of 

 the normal form, but it is a complete loss of 

 the dark-color character which is typical for 

 the normal original strain. 



Lee Bonae. 



Cktptogamic Laboratory, 

 XJniveesitt of Michigan 



A DAMP CHAMBER FOR MICROSCOPES 



In the study of cultures of mycelia of fungi 

 it is desirable that they be observed under the 

 4 mm. objective of the microscope without 

 disturbing the hyphce by transferring them to 

 a microscopic slide and making a fresh mount 

 in the usual fashion. The type of damp 

 chamber described below has been found 

 especially adaptable to this purpose. It af- 

 fords a chamber of considerable volume, with 

 a humidity which is constantly near the satura- 

 tion point, and of such a proportion that the 

 greater part of the enclosed space may be ob- 

 served through the 4 mm. objective. 



This damp chamber is a modification of the 

 one used by Blaauw in his recent work on the 



growth and phototropism of roots. It is made 

 by using a large-sized microscopic slide, 

 2x3 inches, and a large-sized No. 2 cover- 

 glass, 45 X 72 mm., such as are used for mak- 

 ing mounts of brain sections. These two pieces 

 of glass are separated by several layers of 

 filter paper, the central portions of which have 

 been cut out, so that the filter paper is in the 

 form of a frame about 5 mm. in width. Slits 

 in this frame may be made for the purpose of 

 ventilating the chamber, if such is desired. 



The mount is made by placing the filter 

 paper frame on the slide, then dropping a bit 

 of nutrient agar just on the inner edge of the 

 frame and inoculating it with the fungus to be 

 studied. The large-sized coverglass is then 

 placed over the filter paper and the mount is 

 bound together with white linen thread and 

 placed erect in a tumbler containing a little 

 water. It is desirable that the mount be kept 

 in a place which is slightly cooler than the 

 room in which it is to be examined in order 

 that the condensation of water on the inner 

 surface of the coverglass may not interfere 

 with observations. 



This damp chamber has been found by the 

 writer to be an excellent means of preparing 

 mycelia of fungi for use in general courses in 

 botany. Mounts so constructed can be used 

 repeatedly in successive sections of the same 

 or different classes. For this purpose only the 

 low-power, 16 mm., objective is necessary and 

 therefore the coverglass referred to above may 

 be replaced by another large-sized slide, mak- 

 ing the damp chambers much less expensive. 

 The details of the structure of the hyphas are 

 well shown, the normal position in which they 

 develop, and the streaming of the protoplasm 

 in the hyphae of Ehizopus, for example, are 

 very distinct. Also the general form and ar- 

 rangement of the fruiting bodies may be 

 studied here. 



By making a slit in the filter paper f^^ame 

 at one end, this damp chamber may be ad- 

 vantageously used for the study of roots and 

 root-hairs. A seedling with a radicle a centi- 

 meter or more in length may be inserted in 

 the slit and development allowed to proceed. 

 This method of the study of root-hairs even 

 under low power is found to be far superior 



