PRELIMLXAUY ^dTI-: uN THE SILK ^TL.\^-L•^ OY BdMBYX MolU. 21 



views generally accepteil at jne-ent are the fbllowiuo; two : 1) the fibroiu is stKreteil 

 from the posterior ilivision, ami tlio xririii from the middle division (Habereaxdt \ 

 LmxH DE Jeude -\ Mailloi' et I..ambeet "^ etc.) ; 2) the sericiu is formed in 

 the middle division bv some chemical changes jierformed in the jx*riphery of the 

 fibroin mass, which is secretetl from tlie posterior division (Blajxc '\ SLLBERMA2^^' ^^, 

 etc.). Both these views aie, as I believe, occasioned bv failnre in detecting the sericin 

 in the posterior division. On the contrary, I have made ont, in fact, the distinct 

 sericin cover snrr^aniding the fibroin colnmn in the division in question, esi>ecially 

 in the individuals fixed just after a moult. Fixed material reveals not unfi-equently 

 an irregular layar of the fibroin covering the sericin ring ; furthermore, the fibroin 

 layer is connected by its processes with the gland-wall, a fact which atfords imdis- 

 putabV evidence in proving the fibroiu secretion of the middle division. From the 

 fr.ct.s tibove mentionid, I will be p^rmitt^l to draw the following conclusions in 

 regard the silk formation : the fibroin is secreteil not only from the posterior 

 division, but also from the middle division, and that the sericin is transformetl from 

 the fibroin itself under influence of the air in the lumen of the gland. The chem- 

 ical changes in question occur usually in the middle division ; however, tlie 

 proce.<ses take place also in the posterior division, as this is observable in certain 

 periods. The u>ual absence of the sericin in the latter division is due to the 

 transportation of the fibroin which is carried on, in the period of active secretion, 

 .so quickly that the fibroin secreted escapes the chemieal changes therein. On the 

 other hand, the .«<>ricin is formeil abundantly in t!:c middle division simply liecause 

 the fibroin column stays here for an interval of time ample to undergo the chemical 

 action in its pcri]iheral part, b"ing as it were. .<u>taineil by the suddenly narrowed 

 passage from the division in question into tlie anterior division. On the contrary, 

 in the case of inactive secretion, as it hapjK^ns not unfrt>quently in individuals 

 whidi have just finisln^l a moult, the fibroin jiatn rally d<x\- not quiekly leave tlie 



1^; F. H.iberlandt : Der Seidenspinner de?; Maulbeerbaunies. >eine -\nzucht und Krankheiten. 

 Wien. 1871. 



2) Lidth de Jende : Znr Anatomie und Physiologie der Spinndrüsen der Seidenrau}>e. ZcxtI. 

 Anzeig. 1S7S. pp ltX> 102. 



?>) E. Maillot et F. LamVrt : Traite sur le ver a sole du mnrier et sur le nnirier. Monti>ellier. 

 1906. 



4) L. Blanc : Etude sur la secretion de la snie et la structure dt^s hriu ii de la l>avc dan< le 

 ßombytr mori. Lyon. 1889. 



5) H. Silbermann : Die Seide. Dres<len. 1897. 



