82 



RESEARCHES ON FUNGI 



plasmic movements can be seen which suggest that the protoplasm 

 is permeated by a large number of minute, more or less parallel, 

 often anastomosing tubules in the interior of which the granules move. 

 In 1912, Andrews x recorded the results of his studies on the 

 effects of transpiration, osmosis, injury, light, and changes of 

 temperature on protoplasmic streaming in Rhizopus nigricans (his 



Mucor stolonifer), Mucor Mu- 

 cedo, and Phycomyces nitens. 

 For the most part his work 

 served to corroborate the con- 

 clusions which had been arrived 

 at by his predecessors. He 

 remarked that the kind of 

 nutrient medium is of great 

 importance for growing the 

 fungi successfully. By means 

 of a suitable apparatus he was 

 able to change at will the air 

 in the small chamber in which 

 a mycelium was growing and, 

 as a result of using this appara- 

 tus, he found that streaming 

 in a mycelium is strong or weak, 

 the rate varying directly with 

 the intensity of the transpira- 



Fig. 48. — Phycomyces nitens. Effect of 

 light on the vacuoles in germ -tubes : 

 a, a spore which was germinated in 

 darkness or weak light, the vacuoles 

 in its branched germ -tube are few 

 and irregular ; b, the same, a few 

 minutes after having been exposed 

 to sunlight, the vacuoles have in- 

 creased greatly in number. Mag- 

 nification, 345. The drawings copied 

 by the author from Plate I of 

 Ray baud's Influence du milieu sur 

 les Mucorinees. 



tion. In saturated air streaming 

 ceases and, when relatively dry air is supplied, streaming begins and 

 proceeds toward the tips of transpiring aerial hyphae. By means 

 of a fine capillary tube a sugar solution may be applied to particular 

 hyphae of a mycelium completely submerged in a drop of culture 

 medium beneath a cover-glass. Under these conditions streaming 

 takes place always toward the sugar solution and is exclusively due 

 to osmosis. Among Andrews's other conclusions are the following. 

 Injury caused by cutting off the tip of a hypha or by cutting a 

 filament into two pieces may stop streaming altogether ; but the 



1 F. M. Andrews, " Protoplasmic Streaming in Mucor," Bull. Torrey Bot. Club, 

 Vol. XXXIX, 1912, pp. 455-499. 



