494 ANDREWS: PROTOPLASMIC STREAMING IN Mucor 
' ‘TEMPERATURE 
It has been shown by Hofmeister* and others long ago that a 
sudden change in temperature may excite streaming. More 
recently these observations have been confirmed by Hauptfleisch,{ 
Ewart,{ and others, for various plants. The same is referred to by 
Pfeffer,§ and Hérmann|| observed the same result. The literature 
on this subject as regards the higher plants is too voluminous to 
enter into fully here, so that the above brief references must suffice. 
As regards the fungi I can confirm the statements of Schriterf 
that temperature also has much to do with the ability of Mucor 
stolonifer to show streaming. Phycomyces nitens 1 have not 
studied in this respect. I have also found, as in the higher plants 
and as Schréter did for Mucor stolonifer, that a sudden change of 
temperature may produce streaming in those specimens of this 
fungus that were in a condition for such movement. The same I 
have found is true of M. Mucedo. This is the-case whether the 
temperature is raised or lowered suddenly, but with the precaution 
that the change be not too great or continued too long. 
I can not, however, agree altogether with Schréter** that the 
optimum temperature for streaming in Mucor stolonifer is 26° C. 
and for Phycomyces nitens 28° C. My studies have shown that 
the optimum temperature for streaming in M. stolonifer and M. 
Mucedo each ranges from 23° to 26° C. and for P. nitens from 26° 
to 29° C. These temperatures, as given by Schréter, seem to be 
too sharply drawn, for as stated I have found a difference of a few 
degrees Centigrade. I did not attempt to ascertain what effect 
the age of the hyphae had on the optimum temperature for 
streaming, if any exists, as is probable. Ewart} has pointed out 
for some of the higher plants that it is almost impossible to eee 
tain the required temperature exactly or within a degree, owns to 
various factors which enter into the problem and which are not 
* Hofmeister, W. Lehre von der Pflanzenzelle 53, 54. 1867. 
+ Hauptfleisch, P. Jahrb. Wiss. Bot. 24: 210. 1892. 
t Ewart, loc. cit. 66 and literature there quoted. 
§ Pfeffer, W. Plant Physiology 3: 316 and literature there quoted. 1905- 
|| Hérmann, G. Studien iiber die Protoplasmastrémung bei den Characeen 4% 
1898. 
{| Schréter, loc. cit. 56. 
** Schriter, loc. cit. 15. 
Tt Ewart, loc. cit. 60. 
