576 



THE AMEBIC AN NATURALIST 



[Vol. XLI 



formed in this region. This substance is the 'gres.'" He con- 

 siders (pp. 27-28) the "gres" as nothing more than the peripheral 

 layer of silk oxidized in the reservoir, the oxidation being due to 

 the presence of a large number of tracheae in this region. 



In the abdominal portion of the silk glands of Apanteles glomera- 

 ius the secretion appears as a hyaline, faintly staining product. 

 Fixation in Flemming's solution and staining with iron haematoxy- 

 hii gives it a greenish color, the peripheral portion often being 

 l)Uu k. In tlie anterior part of the abdominal portion the peripheral 

 hiyer is always stained black. Safranin colors the entire secretion 

 salmon color, the peripheral layer always more deeply, especially 

 in the anterior part of the abdominal portion. Mayer's acid 

 haemalum and eosin do not color it at all. 



Judging from the staining properties of the secretion the conclu- 

 sion that there is a differentiation between the peripheral layer and 

 the central column appears justified. ^Yhether this j)eripheral layer 

 is the " gres " or not is a question which we do not pretend to answer. 



Thoracic Division. This pf)rtion of the gland remains activelv 

 secreting much longer than the abdominal division. The char- 

 acteristic appearance of an actively secreting ])orti.)n is shown in PI. 

 2, fig. H;. Thv peripheral area often ai)pear.^ k>ss dceplv stained 

 and nnmerons vacnoh-s are always present. 



Tlie character of the sc.-retion' in tiie posterior thoracic <hvision 

 apjK-ars similar to that of the al.doniina! portion except that the 



are generally more nnmerons. It also takes tlu same chai'acter- 

 istic colorations. 



The anterior and middle thoracic portiojis secrete a somewhat 

 (liferent ])roduct. The cliaracter of the cells of the middle portion 

 wonid indicate that snch is the case here at least. Fixation in 

 Fleming's solution and staining with iron haematoxylin gives to 

 this division a vcrv cliaractcristic n[)])earance. The cvto])lasm 

 i> filled uith rather large ronn.lc.l l.ia.-k grannies thns ea.'ilv dilfer- 

 .ntiating this portion from the other two thora-ic .livi>ion>. The 



In .iniilariy tn.ated gland, many identical black grannies are s.^en 

 near th(> interna! >nrfa<r of the cell, jnst within the internal mem- 



the first thoracic division I PI. 1, figs. 10 and 12j. 



