38 



In Corydalis four pairs of suspensoria can be distinguished. There are two 

 pairs of suspensory muscles, a pair of ligaments, and a pair of suspensory 

 nerves. 



The suspensory muscles arise from the body-wall in the thorax, and ex- 

 tend caudad into the abdomen, where both pairs are attached to the aliment- 

 ary canal, and one pair to other viscera also. It is rather difficult to trace 

 out the origins of these threads upon the body-wall ; but the threads can be 

 easily seen extending parallel with the oesophagus and proventriculus, after 

 they emerge from the layer of muscles and fat. They can be rendered more 

 easily seen by staining the specimen with haematoxylin. Empty the water 

 from the dish containing the specimen, and place a few drops of hasmatoxy- 

 lin on it ; after one or two minutes wash off the stain, and cover the speci- 

 men with clean water. 



Study first the suspensoria on one side of the specimen, leaving those of 

 the other side for study when the final drawing is made. In the following 

 notes a single member of each pair of suspensoria is described. 



The two suspensory muscles may be designated as the simple suspensory 

 muscle and the branched suspensory muscle, respectively. 



The simple suspensory muscle arises from near the middle of the ental 

 surface of the pronotum, and extends caudad to the gastric caeca, where the 

 fibers of which it is composed spread apart, some going to one caecum and 

 some to the other. 



Make a provisional sketch of this. 



With fine-pointed scissors, cut off the tips of the two gastric caeca of this 

 side, and remove them with as long a piece of the suspensory muscle as is 

 practicable, and mount them in glycerine for study with a high power of the 

 microscope. Note the transversely striated appearance of the fibers of this 

 suspensorium. This indicates that it is composed of striated muscular tissue. 

 Make a careful drawing showing the minute structure of this suspen- 

 sorium. 



The branched suspensory muscle arises from the ental surface of the body- 

 wall, on the dorsal side, between the mesothoracic and metathoracic shields, 

 near the lateral margin of the body and extends caudad into the cavity of 

 the abdomen ; here it divides into several branches. One branch extends 

 to the ventriculus ; one or more to the masses of fat and to the Malpighian 

 vessels ; and one joins a suspensorium which extends from a large trachea 

 hi the third abdominal segment to the intestine. 



Trace out the course of the branches of the branched suspensory muscle, 

 and make a provisional sketch showing their connections. 



