ANDREWS: PROTOPLAS).1C STREAMING IN MucoR 467 
fer, and in all cases large active growing hyphae were obtained. 
So far as could be ascertained from a great many cultures prepared 
in this way, all of the fungal spores just mentioned above seemed 
to grow about equally well. The temperatures were controlled 
by placing the cells containing the specimens in a constant tempera- 
ture room in Pfeffer’s Institute. A change of temperature, even 
though it be very slight, may sometimes cause an acceleration 
or retardation in protoplasmic movements. To prevent this the 
microscope and all apparatus concerned in such experiments were 
also put in the constant temperature room at the time the culture 
was started, in order to avoid a change of temperature, which 
would occur if the cell were placed on the colder surface of the 
stage of the microscope. 
In such an investigation as this, where the temperature was 
to be considered, some experiments were carried on in the constant 
temperature room at 24° C. A more convenient way for the 
investigator is, in case the cover glass is properly attached, to make 
use of a warm chamber like that of Pfeffer* or that of Ewart.t 
Another rather convenient and exact way to control the tempera- 
ture of the specimen for an indefinite period is by the use of the 
Molischt freezing-box, in which the ice ordinarily employed is 
replaced by water of the desired temperature, which is siphoned 
in and out. The best and most exact method of controlling the 
temperature is to arrange an ordinary thermostat having an 
adjustable glass door. The microscope may be placed in the 
thermostat and operated as in the Molisch freezing-apparatus. 
The heat may be exactly regulated by means of a thermoregulator. 
In the study of the effect of temperature I did not attempt to 
ascertain what result the optimum temperature had on the hyphae 
of very different ages, if it has any, as is probable. Ewart§ has 
shown this to be the case in the cells of Nitella and Chara, At 
all events an investigation to ascertain this exactly in various 
fungi is much to be desired. The following two experiments will 
show the behavior of the protoplasm when saturated air and aif 
* Strasburger, E, Das botanische Practicum 3: 22. 1887. 
t Ewart, A. J. Protoplasmic streaming in plants 60. 1902. 
t Molisch, H. Untersuchungen iiber das Erfrieren des Pflanzen 2-6. 1897. 
Ewart, loc. cit. 63. 
