220 



SCIENCE 



[N. S. Vol. XXXVI. No. 920 



numbers, but later they surround the tracheae 

 in curious cyst-like clusters. Still later the 

 other cells become filled up with them and 

 finally, when the caterpillar dies and disinte- 

 grates, they escape into the body fluids. The 

 polyhedral bodies, to be sure, behave as crys- 

 tals, but, not finding at the time anything of 

 interest in the tissues, we gave them consider- 

 able attention, confirming Escherich's various 

 chemical tests and staining reactions. That 

 the polyhedral bodies might be organisms, per- 

 haps distantly related to the microsporidians, 

 seemed inconceivable; still their curious cyst- 

 like arrangement around the tracheae helped 

 much towards concentrating our studies upon 

 them. They revealed nothing, however, which 

 could in any way be associated with parasitism 

 and were finally abandoned as mere reaction- 

 bodies, possibly urates. They react fairly well 

 to the murexid test, giving all the color reac- 

 tions except the last one. Why we have been 

 unable to obtain this last reaction we are at 

 present unable to say. We find that these 

 bodies can be readily centrif uged out from 

 sick and dead caterpillars and in quantities 

 sufficient for purposes of chemical analysis, 

 and we hope to be able to give a more intel- 

 ligible account of them later. Nevertheless, 

 as has always been supposed, the polyhedral 

 bodies seem to have some significance, for 

 after using good light and very high magnifi- 

 cation small wriggling organisms were ob- 

 served in the fat cells and other cells at such 

 times as the polyhedral bodies were clustered 

 around the trachea. These moving organisms 

 were stained and found to be bacteria. From 

 this time on we pursued the work along bac- 

 teriological lines and we believe have been 

 able to demonstrate the etiological connection 

 of these bacteria with the disease. 



Living caterpillars are the only ones which 

 can be treated with fixing fluids for section- 

 ing. When a caterpillar dies of the wilt the 

 degeneration of the tissues is so rapid that it 

 is impossible to handle it. When touched, it 

 goes all to pieces and therefore can never be 

 used for histological work. Some of the , sec- 

 tioned material showed that hardly any of the 

 tissues failed to reveal the presence of, this 



bacterium. It was found in great numbers in 

 all parts of the intestine and in many cater- 

 pillars appeared to be in the act of perfo- 

 rating its walls. The fat cells seem to be par- 

 ticularly liable to attack, which probably ac- 

 counts for the saponified nature of the fat of 

 sick caterpillars. The musculature, ganglia, 

 testes, ovaries, cenocytes and other cells are 

 also heavily parasitized. In fact, as previ- 

 ously stated, nothing seems to be exempt, since 

 the infection extends even to the hypodermal 

 cells. Some larvae show a heavier degree of 

 parasitism than others, while a certain num- 

 ber apparently not diseased may be free from 

 the bacteria. 



The organism in question is very small, 

 having a diameter of only .51 /i-.85 /x. It re- 

 sembles Pneumococcus very closely except 

 that it is motile, progressing in a gyrating 

 manner. For this reason, and because it seems 

 to be an undeseribed form, we have named it 

 Oyrococcus. A brief technical description of 

 it is given at the end of this paper. 



Smears of dead larvae were now studied and 

 after making the smears very thin and using 

 Griibler's Giemsa or Delafield's haematoxylin 

 with eosin, the Gyrococci were more clearly 

 revealed. Owing to their minuteness it is al- 

 most impossible to see them in thick smears. 

 They are also apt to be obscured by the poly- 

 hedral bodies, which are very abundant in dead 

 material, so that smears must be thinned out 

 with sterile water in order to separate these 

 bodies. Then only can the Gyrococcus be 

 recognized easily under the 2 mm. oil immer- 

 sion in combination with the compensating 

 12 or 18 ocular. In material which has been 

 dead a long time many different species of 

 septic bacteria accumulate, but caterpillars 

 which have just died are fairly pure except for 

 the Gyrococci which are present in large 

 numbers. 



In order that the non-pathogenic forms 

 might give us as little trouble as possible, we 

 inoculated sterile veal tubes with the fat of 

 living infected material. These tubes were 

 kept in an inseetary where the temperature 

 fluctuated during May, June and July between 

 80° and 95° Fahrenheit. We thought, that 



