Francis E. Lloyd 



170 — 



Carnivorous Plants 



thought. After the animal succumbs, branches from the loop penetrate 

 its body, and withdraw nutriment (Text fig. 4). 



What happens in the case of another similar organism, Dactylella 

 bembicoides Drechsler, was explained by Couch (1937). In this 

 plant the loops are composed of a short branch of three cells turned 

 upon themselves. Fusion occurs between the end and basal cells, 

 and a neat ring is thus formed. By growing the fungus on agar 

 to allow of clear microscopic observation, he saw an astonishing thing, 

 that when an eelworm pokes his head or tail into a ring, the ring 

 immediately clamps on it by the sudden swelling of the three cells 

 (Text fig. 4, d, e, i). Couch records his opinion that the rings are 

 formed most abundantly in media poor in "available food supply," 



Fig. 4. — A, B, Zoophagus insidians (after Gicklhorn 1922); C, Dactylella tylopaga 

 attacking Amoeba (after Drechsler 1935^); D, E, F, Dactylella bembicoides which attacks 

 nematodes (after Couch 1937); G, H, Arthrobotrys oligospora, which attacks nematodes 

 (after Zopf 1888); I, Dactylella betubicoides (after Couch). 



judging from experiments which he did. He attempted to get rings 

 to close on fine glass rods, with limited success, so that it seemed 

 unlikely that mechanical stimulation suffices. He did find, however, 

 that heat (water, at t,3 to 75° C.) will cause the rings to close, 

 but that the temperature of the animal's body enters in as a factor 

 in nature is quite unlikely. Couch therefore fell back on the perhaps 

 correct explanation that the fungus responds to a chemical stimulus 

 from the worm's body. A 1% solution of lactic acid caused a slight 

 swelling. While this was uncertain. Couch observed that in every 

 case "when a nematode thrusts its head or tail into one of the rings 

 it closes practically instantaneously by the simultaneous swelHng of 

 the three cells of the ring." Later, new hyphal branches penetrate 

 the body of the prey. Among these predacious species are included 

 Trichothecium, Arthrobotrys, Dactylaria, Monacrosporium and Dactylella, 

 all figured by Drechsler (1934a). Still others may be expected to 

 turn up. 



But not all the ring forming fungi act in the same way. We owe 



