EXPERIMENTS UPON THE LEPIDOPTERA. 225 



as between the seventh and eighth segments. The section in 

 the posterior component varied within narrow limits, sometimes 

 passing far baclc of the eyes just anterior to the roots of the 

 wing cases, sometimes being anterior to the eyes. In many 

 cases, where but a little was sliced off, the posterior component, 

 esj^ecially if far advanced, simply healed over its own wound 

 and emerged independently, without the slightest attempt to 

 coalesce with its fellow pupa. Five operations of this kind 

 were made upon cyntJiia, with one successful coalescence. This 

 specimen is of the greatest interest. Unfortunately, a photo- 

 graph illustrating the important details cannot be taken, and 

 hence no illustration can be given. The interest lies in the 

 fact that from the posterior pupa of the " tandem " were cut away 

 the entire head, — eyes, brain, and all, — the basal portions of 

 the sacs of the antennae and mouth parts, as well as a portion 

 of the prothorax. The result is that in the coalesced moths 

 all of these parts are absent. The weakly developed antennae 

 and mouth parts of the hinder moth arise directly from the 

 narrow circular sheet of regenerated tissue which spreads from 

 the last abdominal segment of the anterior component to the 

 remains of the j^rothoracic ring of the posterior component. 

 The microscopic study of the internal conditions of this double 

 specimen will assuredly furnish some very interesting data. 



The experiments of this group which would have been of 

 the greatest value, if successful, were those where male and 

 female proviethea were united. Out of six operations not one 

 gave results, and hence no data for the determination of 

 reciprocal color effect could be here obtained. 



Union of cynthia and pronietJiea, however, gave out of six- 

 teen cases two remarkably fine fusions. One of these is shown 

 in Fig. 3. The components were both female, the pi'omcthea 

 being posterior. Unfortunately, the wings of both failed to 

 expand, although the moths lived for five days, until chloro- 

 formed. The other case was that of a female cynthia anterior 

 most firmly united to a pi'omethea male posterior. The moths 

 of this compound also failed to expand their wings. 



These two cases do not furnish any very definite data bear- 

 ing upon the color question. It is true that in the first case 



