December/13] GLASER AND CHAPMAX: GIP8Y MOTH WILT DISEASE 481 



As stated in our first paper dead caterpillars cannot be sectioned 

 owing to the fact that they disintegrate completel}' after death. If 

 serial sections are made of diseased caterpillars obtained in the field, 

 polyhedral bodies will be found in abundance, but no bacteria in the 

 tissues and in most cases the intestinal lumen will be perfectly free 

 from microorganisms in general. This is a very striking fact when 

 compared w4th the abundance of intestinal flora in the higher animals. 

 Last year we stated that we had observed small wriggling things in 

 the tissues which after being stained were revealed as Gyrococci. 

 Small WTiggling or rather dancing things are certainly found in the 

 tissues of diseased caterpillars, and it is possible that we mistook these 

 for Gyrococci. Pigment granules are also easily confused with bac- 

 teria as anyone knows who has studied the pigment granules in the 

 basement membrane lining the hypodermis, and in the ganglia. The 

 microorganism described as Gyrococcus flacciclifex when found proves 

 to be an intestinal invader pure and simple. We will return to the 

 small wriggling particles later. 



Methods Used for Obtaining Healthy Material 



After we realized that it was futile to depend upon the blood test 

 for obtaining healthy material and that it was impossible to be cer- 

 tain of any material in the vicinity of the laboratory, field men were 

 asked to report any places in the infested territory where the disease 

 was not evident. As soon as such places were reported, we visited 

 and carefully examined them ourselves. If any dead caterpillars 

 were found and later on microscopical examination showed polyhedral 

 bodies, living material from such a locality was not used. Caterpillars 

 were only taken from places where the disease could not be found at 

 the time of collection. The objection will at once be raised and rightly, 

 that the disease may have been there in a latent form and that no one 

 can tell by an external examination whether a caterpillar is healthy 

 or not. We have studied the disease in the field as well as in the 

 laboratory and have found it in all of the infested territory from Maine 

 to Rhode Island. It wtII at once become evident what a difficult 

 matter it is to obtain healthy material for experiments. Apparently 

 the healthiest looking colonies harbor a number of diseased individuals, 

 for sooner or later, if the place be carefully watched, the disease will 

 appear. Then after all, the critic Avill say, you obtained your experi- 

 mental material from a diseased locality. This is quite true, l)ut the 

 disease if present had not taken the form of an epidemic in such locali- 

 ties when the collections were made and the chances of obtaining some 

 healthy individuals were very great. In places where the infestation 

 is light and the caterpillars widely separated, the disease never reaches 



