406 ■ 



sometimes several such strips may be present. Most usually, 

 however, the leucocytes remove the muscle tissue in much 

 smaller quantities. Pseudopodia, however, are very rarely 

 seen; although the absorbed food is frequently contained in 

 a vacuole, and although it is possible that during the killing 

 of the leucocytes, in making the preparations, pseudopodia 

 may have been withdrawn, it is nevertheless quite probable 

 that a considerable amount of feeding takes places by the 

 absorption of liquid material, perhaps dissolved by extra- 

 cellular enzymes directly through the walls of the leucocytes. 

 I shall refer to this again later. 



That the muscles, once their sarcolemma has been rup- 

 tured, may undergo' a certain amount of ''chemical disintegra- 

 tion" is not unlikely; it might, however, be very difficult to 

 detect microscopically. In the case of the vertical abdominal 

 and the pharyngeal muscles, however, it does occur, and is 

 (^fairly easily seen (see below). Nevertheless, the main factor 

 k ) in the removal of the degenerated fibre is the phagocytic action 

 L of the leucocytes. These scavengers, having gorged them- 

 selves at the expense of the dead tissue, gradually move to 

 some secluded corner in the cavity of the appendages, or 

 amongst the developing integumental cells, and there attempt 

 to digest their meal in peace. 

 ( — The removal of the dead muscles is accomplished within 



I several hours; ten hours after pupation they have entirely 

 I disappeared. 



(h) The Vertical (oblique) Abdominal Muscles. 



Although myoblasts may, in the anterior part of the 

 abdomen, develop in relation with some of the degenerating 

 vertical muscles, yet the appearances which these present, as 

 they disintegrate, are quite different from those which we see 

 in the longitudinal muscles. 



The nuclei present the usual features of a greatly hyper- 

 trophied nucleolus, often containing numerous minute 

 crystals. Tlie contractile part of the muscles may disintegrate 

 at a remarkably early period, viz., in the defaecating larva; 

 at other times distinct striations may still be seen a day 

 later. Almost invariably, however, the striations have dis- 

 appeared from the muscles sixteen hours after defaecation, 

 and the resulting appearance of the muscle depends upon 

 whether the contractile substance has been cast bodily out 

 of the fibre, or whether it has become uniformly scattered 

 along the fibrillae. Both these processes occur. I shall first 

 describe the former. 



It was in one of the posterior abdominal muscles in the 

 larva at about the time of defaecation that I was able to 



