254 SEA-SIDE STUDIES. 



seqiiently be without blood. Even so. Without " blood " 

 it is, unless we extend the term " blood " to every fluid 

 fulfillino; the office of a nutrient fluid ; an extension not 

 only oblitercating the whole purport of exact language in 

 science, but finally reducing us to the state of the Irishman 

 who saw in a lake " all the materials for punch — barring the 

 whisky and the sugar and the lemons ; " since when we descend 

 to the simplest forms of organisation, we reach a nutritive 

 fluid which is water, and nothing more. Dr Thomas Wil- 

 liams, to whose researches on the blood we owe grateful 

 acknowledgment, considers that in the Echinodermata the 

 blood-proper first makes it appearance ; below that point 

 there is no blood, but only chylaqueous fluid ; and even for 

 several stages higher, this chylaqueous fluid continues to 

 hold its place beside the true blood ; so that a worm, for 

 instance, has two fluids — blood, circulating in a system of 

 closed vessels, and chylaqueous fluid oscillating in the general 

 cavity outside the vessels.* 



It is indispensable, in philosophic zoology, to discriminate 

 between hlood, a fluid of definite constitution circulating in 

 a system of vessels, and the chylaqueous jiuid, formed of 

 water and the products of digestion, oscillating in the general 

 cavity. But my investigations lead to a still further reduc- 

 tion of this latter fluid ; and instead of saying with Dr 

 Williams that the simplest condition of a nutritive fluid is a 

 " very dilute solution of albumen in sea-water," -f- 1 am forced 



* See page 68. 



t See his paper on " The Blood " in the Brit, and For. Med. Rev., Oct. 1853, 

 p. 480. 



