G6 
culture used in experiment 1. One of the larvae was almost grown, one about half 
grown, and the others younger. 
The following day, July 9, the drenched leaf had been almost entirely eaten up. 
They were left to feed upon the remains until the second day, when a fresh leaf was 
placed iu. 
Up to July 14 no symptoms of disease appeared in any of the larvae, and on that 
day the last two pupated. July 15 the two oldest pupae died. One of those had 
heed noted as turning darker the previous day as if beginning to rot. To-day its 
wing-covers and head are entirely black, while the abdomen practically retains the 
normal color. The other dead pupa is entirely of a uniform dusky color. The two 
living pupae were lying just alongside the two dead ones, and were thoroughly ex- 
posed to infection, if any. Both, however, hatched, one on July 18, the other 
July 22. 
Experiment S. 
July S. — The culture liquid used was the same as in experiments 1 and 2. A small 
cabbage leaf was drenched and four Pieris rapce larvsB placed to feed. Two of (hem 
were nearly grown, the others about half grown. By July 10 the leaf had been en- 
tirely eaten, but no symptoms of disease were noted. Fresh leaves were placed in 
July 13. July 15 two pupae were found, one being imperfectly formed. The two 
remaining larvae fed freely, but did not seem to grow as rapidly as usual. At times 
their skin seems to be somewhat puckered and appears rather dusky. July 16 the 
ill-formed pupa is dead. July 18 the last larvae pupated. July 27, without any 
apparent outward changes to forewarn such a result, it was found that all the pupae 
had died. About the time of death, or soon after, the color becomes slightly brown- 
ish or dusky. The special attention due this experiment was frequently interrupted 
and fresh food was not provided the larvae as often, perhaps, as was conducive to 
their best development. This may have induced them to attempt pupation rather 
prematurely, or have weakened them so as not to be able to cope with the germ. 
Checks on experiments 2 and 3. 
The larvae in experiment 1 having completed their transformations without diffi- 
culty, a consideration of its check will not be necessary. For experiments 2 and 3 
a number of Pieris rapes larvae were placed upon cabbage leaves in a separate jar to 
act as a cheok. 
July 9 the following was the condition of the larvae in the check : 1 pupated, 3 
pupating, 4 grown, 1 half grown, and 3 younger. Up to July 16 the younger larvae 
had kept on feeding perfectly, and succeeded in maturing and pupating. Two 
adults issued on this day, and one pupa, which had been injured a few days before, 
was dead. July 17, 8 pupae remained. Two had become darker in color, as if begin- 
ning to decay internally. Later these 2 were found to be certainly dead, the one 
having turned quite blackish, the other more brownish gray. The other 6 hatched. 
One of the dead pupae of experiment 3 was taken for further study. The contents 
were a blackish liquid mass, from which a drop was taken with which to inoculate 
a tube of broth. From this other liquid cultures were made, and from these pure 
cultures upon agar-agar were obtained by the ordinary process. One of the dead 
pupa> was taken from the check for a similar study. Its contents were of the same 
nature as of the one just noted. In the same manner liquid cultures, and from these 
pure cultures upon agar-agar were obtained. A careful comparative study proved 
that the pure cultures obtained from the two pupae were identical, and a microscopic 
study developed the fact that both were cultures of the Micrococcus of the cabbage- 
worm disease. Accordingly the pupae in experiments 2 and 3 did not come to their 
deaths solely through the agency of the boll- worm disease, though the greater per 
cent of deaths in the experiments, as compared with that of the check, would indi- 
cate that the latter germ contributed in some manner to this end 
