[7J ON MERMIS ACUMINATA. 119 



Upon submitting the specimen with which you favored us, 

 to microscopic examination, it was seen to differ in its internal 

 structure and in its more pointed extremities, from the species 

 of the genus GORDIUS above referred to. As these forms have 

 been so little studied and so little is known in relation to them, 

 it was deemed proper before naming it for you in accordance 

 with your request, to submit it to the eminent authority, Dr. 

 Leidy of Philadelphia, who has given special study to the 

 Entozoa. Having examined it, he returns the following very 

 interesting information : " The worm is a species of MERMIS, 

 a parasite of the larva of Carpocapsa pomonella, or apple- 

 worm moth, which accounts for its presence in the apple itself. 

 A similar specimen was referred to me a short time since, for 

 an account of which see the next or forthcoming number of 

 the Proceedings of the Academy of Natural Sciences [Phila- 

 delphia]." 



MERMIS is a genus closely allied to GORDIUS. . Leidy states 

 that he has frequently seen specimens of it, which he calls 

 "the white hair-worm," within insects in one instance crawl- 

 ing out of a Carolina grasshopper which was struggling in a 

 ditch. Siebold describes Mermis albicans of Europe (two to 

 five inches long, of a whitish color) as parasitic in the drones 

 of the honey-bee. 



This new phase of parasitism of the Mermis upon a cater- 

 pillar living within the apple, at its core, and often in its 

 younger stage within the seeds, is so remarkable and interest- 

 ing an announcement, that we shall anxiously await the 

 promised paper, for the explanation of much that seems 

 mysterious to us. In what manner, and at what time, does 

 the Merrnis effect its entrance in the body of the Carpo- 

 capsa apple- worm ? The eggs of the apple- moth are depos- 

 ited on the blossom end of the apple, where the skin is the 

 thinnest, at various periods during the summer months. 

 Hatching within a week, the young caterpillar passes directly 

 into the apple, eating its channel as it proceeds toward the 

 core. Here it remains until it has completed its growth, when 

 emerging from the apple it crawls down -the branches, or 

 drops itself to the ground by its thread, to seek some safe 

 place of shelter in which to construct its cocoon. At this time 

 and even during its subsequent hybernation in its larval form 

 within its cocoon, it is exposed to parasitic attack ; but this 

 cannot be the period of the entrance of the Mermis, for its 



