DR Wright's observations. 181 



tion of the intestinal element passed through the stolon 

 from the old into the new body. These new polypes 

 were not young ; their production was a simple increase 

 of the individual, becoming afterwards a multiplication, 

 either by accident, in some cases, or in others by a 

 natural process of absorption. The structure of the 

 helianthoid zoophytes or Actinias was more compli- 

 cated in its development than that of the hydroid 

 polypi, but it consists of the same three elements, The 

 dermal coat was succeeded by the muscular element, 

 which constituted the chief part of the external wall of 

 the body and tentacles, and then passed inward to the 

 stomach, in the form of septa or partitions, which sus- 

 pended that viscus in the centre of the body, and 

 divided the intervening spaces into numerous cham- 

 bers. The mucous or intestinal element existed as a 

 flattened sac or stomach, which appeared, when viewed 

 edgeways, as a mere line extending down about half the 

 centre of the body. The stomach communicated freely 

 with the general cavity of the body. This cavity, 

 which corresponded to the water- vascular system of the 

 Acalephse, was single below, but as it passed upward it 

 formed a number of chambers divided from each other 

 by the septa before mentioned, and finally communi- 

 cated with the tentacles, each chamber termmating in 

 the cavity of a single tentacle. 



" The whole of the general cavity and its chambers 

 was lined with cilia, by which a constant circulation of 

 the fluid was sustained, and the functions of nutrition, 

 respiration, and excretion were all carried on simulta- 



