October, 16] ROCKWOOD: SPOROTRICHUM ENEMY OF ALFALFA WEEVIL 495 



show this fluffy, cottony growth which sometimes spreads out over the 

 rotting debris to an area of one half inch or more. Under the usual field 

 conditions or in well ventilated, well lighted cages, the fungus forms a 

 dense felted mass, usually confined to the elytral, thoracic, and ab- 

 dominal sutures, which are often completely outlined by the white 

 l)ands of the fungus mycelium. Upon this short felted growth of 

 mycelium, the balls of spores appear densely packed together. Old 

 specimens of the fungus assume a well-defined cream color. 



It was found by experimentation that the macroscopic appearance 

 of the fungus on weevils killed by mechanical or chemical means before 

 exposure to the fungus presented a relatively different appearance from 

 that on weevils killed by the fungus. In the case of weevils killed before 

 infection, the fungus appeared as a very thin, long, loose, cottony cover- 

 ing, almost cloudy in appearance, nowhere localized in a thick mass. 

 Moreover, in all such cases, contamination of the typical fungus with 

 the well known saprophytic fungi of the genera Penicillium and Mucor 

 invariably occurred under the somewhat septic conditions incident to 

 the experiment. Weevils killed by the fungus always developed a 

 pure dense growth of the typical fungus, and saprophytic fungi never 

 developed upon them until after the parasitic fungus had matured and 

 disintegrated. Weevils killed by the fungus are usually found in a 

 life-like attitude with legs and antennse extended as if death overtook 

 them suddenly while on the move. 



Laboratory Experiments 



No cultures of the fungus in artificial media were attempted. Spore 

 germination studies by the hanging drop method in Van Tieghem cells 

 were made for the purpose of gaining information for the better in- 

 terpretation of dissections and blood examinations. The formation 

 of the so-called " cylinder-gonidia" of DeBary^ were thus studied and 

 later identified in the blood of infected weevils. 



Several infection experiments with S. glohuliferum on H. variabilis 

 (posticus) were carried on in the laboratory at different times, always 

 with 90-100 per cent mortality from the fungus. The infection cages 

 varied from tightly closed tin tobacco boxes with bottom layers of 

 moist sand or garden loam on which the weevils and their food were 

 placed, to open glass battery jars on the bottoms of which was placed 

 moist sand or garden loam to a depth of one-half inch to three-fourths 

 inch, the food and weevils being then introduced and the jars closed 

 with cheesecloth tops, thus allowing the air free access to the interior 

 of the cage. These cages were moistened from time to time as they 



^DeBary, A.: Comparative Morphology and Biology of the Fungi, Mycetozoa 

 and Bacteria, p. 372 Oxford. 



