m ^ m m 



PRELIMINARY NOTE ON THE SILK GLANDS 



OF 



BOMBYX MORI. 



YOSHIMARO TaNAKA. 



SericuUural Luhomtonj of the College of Agriculture, 

 Tohohi Imperial University. 



In my recent studies on tlie silk glands of the domestic silkworm (Bomhyx 

 'iiwrij I come to conclusions differing greatly from those of previous authors. I 

 Mill enumerate in the following pages the cliief points obtained. 



1) There are two pairs of long slender muscles standing in relation to the 

 silk glands. A pair of these muscles attaches to the middle division ^\ and the 

 other to the posterior division of the glands. They tie up various parts of the silk 

 glands by means of connective tissue tendons. As it a])pears to me, they afford in 

 this way an important service to give to tlie glands the certain foshion of its loop- 

 iugs and convolutions. Concerning their histological nature, the silk glands them- 

 selves are, in contra.st to the remarks made by A. Lenticchia "-\ not muscular 

 at any rate. 



2) Numerous tracheal tubes of various sizes stand in connection with the 

 middle and the posterior division, but not with the anterior division at all. These 

 tracheal tubes not only supply air to the secretoi-y cells, but they are subsei-ved in 



1) In tlie silk gland there are generally distinguished four parts, respectively named filiere, 

 excretory tube, reservoir and secreting tube, according to the physiological function of each part which 

 is so a.ssumed. As will, however, be seen m future pages, this assumption is partly incorrect. I 

 prefer, tlierefore, the terms anterior, middle and posterior division for last tliree parts, while the term 

 filiere is retained. 



2) BoUettinn di Ser.imltvra. Anno XIII, No. 46, pp 468, 1906. 



