358 Anatomy and-Physiology of the Family Nepide. (April, 
sinus. According to Milne-Edwards this has some claims to be 
considered the auricle of the heart, since its muscles help fore 
the blood through the afferent openings into the heart. In add 
tion to the triangular muscles, the heart is attached in the w 
by a single triangular piece of connective tissue. 
The heart beats rhythmically, its activity depending gray 
upon whether the insect is quiet or excited. As near asl 
conclude, the normal number of beats in Belostoma larve is abot 
forty-five per minute. In those confined in glass boxes the num 
ber of beats were from thirty-four, to sixty-three, pc minute. 
The contraction of the different chambers is not quite synch 
nous; the back chamber contracts first, then the others fallow 
nick succession, so that the blood is kept constantly moving for 
wards. At the beginning of the diastole of the heart, tlà vals 
guarding the afferent openings bend inward witha quick, almot 
jerking motion, and permit the entrance of blood fon A 
cardial sinus; upon the systole of the heart the peri i 
receives an accession of blood from the chambers teac 
the closing of the valves of the afferent openings gh 
return of blood from the heart to this cavity, It has ws 
mined by the investigations of Dogiel,and others, that the il 
kept beating by ganglionic corpuscles, like the heart in ve ne 
The course of the blood is forward in the heart ma 
vous ganglia of the head, where the aorta ends in oa bat 
expansion. From here the blood is thrown into E E 
which are regular channels leading through the conn a 
and among the organs of the body. Although there ou : 
arteries and veins, the course of the blood is reg ari 
lacunæ, and the heart may be easily injet by: of ht 
into the body cavity. I have often inj heart 0 Theil 
ide by throwing carmine into the ventral oe 
passes into the legs, wings, antennz, etc 
two large currents passing backward along 
ultimately it gets back to the pericardial sinu 
the heart to begin its course anew n the circ" 
The Pulsatile Organs of the Legs. . —Accessory the three PF 
is a special system of pulsatile organs, found in just 
the tibia J 
legs of these insects, generally situated in ial k 
articulation with the femur. In the raptora ^ 
however, the organs are in the clasp joint, 
articulation with the tibia. 
