64 MULLER ON THE MALE OP 



especially in one specimen, in which I found after the circulation 

 had ceased, a sacculated space '15 of a line long by 'OlS-'OS 

 broad in one of the longitudinal vessels of the back, somewhat 

 behind the extremity of the seminal capsule. At both ends of 

 the dilated portion more delicate lateral branches were given off. 

 Somewhat further behind upon the same vessel, and in a corre- 

 sponding position upon that of the other side, there was a 

 rounded expansion of -OS-'OG of a line in diameter. If these 

 dilatations are to be called hearts — in which case they might be 

 considered to undergo a further development — we must suppose 

 that such exist in many places, which would agree with the 

 general arrangement in the Cephalopoda. 



But it may well be that these spots had merely remained ac- 

 cidentally dilated after death, for the narrower parts of the ves- 

 sels were evidently contracted, and one of them, further on in 

 the thick part of the body, was evenly dilated to 005 of a line. 

 The differences in breadth, which may be successively observed 

 in the same place during life, are again very considerable. A 

 vessel between the axis and the seminal capsule measured in its 

 condition of expansion 0*05 of a line, and contracted to '02 of a 

 line. 



This rhythmical expansion and contraction of the larger ves- 

 sels goes on in somewhat different modes. Frequently one por- 

 tion of a vessel is suddenly distended by the wave propelled by 

 the contraction of that portion which lies immediately behind it, 

 and then collapses again. At other times one part is slowly dis- 

 tended by the blood which streams in gradually, especially out 

 of the smaller vessels, and at last contracts with a jerk, whereby 

 the vessel in consequence of its elongation becomes much bent. 



The independent share of single portions of the vascular 

 system in the centripetal movements of the blood is very clear 

 here as in other parts of the Cephalopoda, e. g. the gills. 



More or less rhythmical and swift contractions are seen to 

 drive the blood from the smallest venous twigs into the larger 

 trunks ; these help it on further either by an immediate contrac- 

 tion, which is a continuation of that of the smaller branches, or 

 only after they are more dilated by the repeated contractions of 

 the latter. That this venous movement is nowise propagated 

 from the arteries, is clear from the circumstance that single 



