222 



SCIENCE 



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



twelve inoculated in the dorsal vessel died, the 

 remaining two are still pupae. All of the 

 deaths were tj^jieal of " flacherie." Of the 

 two lots used for feeding experiments all died 

 without a single exception. All of the con- 

 trols survived and pupated, and some of these 

 have already become moths. 



It will be noticed that some caterpillars 

 seemed to be more resistant than others or 

 perhaps they may not have received as large 

 a dose and consequently were longer in dying. 

 The feeding experiments were particularly 

 successful, all of the caterpillars succumbing 

 within nine days with the typical symptoms 

 of " flacherie." We performed several series 

 of experiments similar to the ones outlined 

 above and the results in general agreed very 

 well with those of the described series. That 

 the feeding experiments were more successful 

 than the others may be accounted for in one 

 of two ways. First, in feeding we evidently 

 gave them a larger dose, for our inoculating 

 needles are very fine indeed to avoid injury to 

 the caterpillars and consequently the number 

 of Gyrococci introduced by inoculation must 

 be considerably less than the number intro- 

 duced by feeding. Second, the infection nat- 

 urally enters by way of the mouth with the 

 food, for sectioned material shows that in 

 some cases while none of the cells are as yet 

 attacked, the proetenteron is nevertheless 

 heavily infected. As soon as a caterpillar 

 died it was carefully examined and those 

 which died as a result of the two methods of 

 feeding were found to be much more heavily 

 infected than those which died after the inoc- 

 ulating experiments, although in the latter 

 case the number of bacteria was great enough 

 to have caused death. 



Whenever any of the control experiments 

 died, which did not often happen, we could 

 always trace it to carelessness on our part, for 

 careful reexamination of our original blood 

 slide sufficed to show that the Gyrococcus had 

 been present and had been overlooked. In 

 nearly all cases we were successful in obtain- 

 ing moths from our controls. 



It was very interesting to see the influence 

 which the temperature exerted on these ex- 



periments, for on hot days three times as many 

 caterpillars died of the disease as on cool days. 

 Two such cool days are represented in the 

 table by the third and fourth dates, when not 

 a single caterpillar died in any of the experi- 

 ments. We do not mean to say that tempera- 

 ture is the only factor which is of importance, 

 but its activating power is as striking in the 

 laboratory and insectary as it is in the field. 

 For this reason we believe caterpillars iu their 

 first, second and third instars usually escape 

 not because they are small, but because when 

 the caterpillars are still in these stages the 

 weather is comparatively cool and the food is 

 still plentiful even in heavily infested locali- 

 ties. Bad food or lack of food also bears an 

 intimate relation to the period of life at 

 which a caterpillar may die of the disease. 

 Poor or insufficient food must obviously lower 

 a caterpillar's vitality and weaken its powers 

 of resistance. 



In each series of inoculating experiments a 

 few caterpillars survived and pupated. Some 

 died with the disease during this stage, while 

 a few transformed. When the latter were ex- 

 amined the body fluids and tissues of the 

 moths were found to be full of Gyrococci and 

 the ovaries were also infected, showing the 

 great possibility for the transmission of the 

 disease to the offspring through the eggs. In 

 fact, there are two things which suggest that 

 " flacherie " may be transmitted in this man- 

 ner. First, caterpillars which are reared from 

 eggs and kept isolated contract the disease 

 independently of one another. Second, we 

 have found the ovaries of material used for 

 experimentation as well as some of the 

 ovaries dissected from moths caught in the 

 field to be infected. In the males, however, 

 we have been unable thus far to find Gyro- 

 coccus either in the seminal fluids or in the 

 spermatozoa. Hence we conclude that the 

 transmission of the disease is probably ac- 

 complished through the eggs, although up to 

 this time we have not had time to section any 

 of these. 



To exclude the possibility of having really 

 inoculated an ultra visible virus together with 

 the Gyrococcus, a. large number of caterpillars 



