ON WANDERING CELLS IN ECHINODERMS, DU 
those requiring much nutriment; (3) in other Echinoderms 
(Echinids and Holothurians) there are more definite vessels 
which have a “ parallel” distribution. 
Since in Asterids the tubes containing fluid and the leuco- 
cytes infiltrating the walls of these tubes are associated together 
everywhere, I cannot agree with Hamann in considering that 
“blood lacunze”’ RUN oN the “ chromatogen organ:” the whole 
of the hemal system is “ chromatogen organ,” and contains 
“blood lacune;”’ the two are inseparably bound together 
in Asterids, though in other Echinoderms there is more diffe- 
rentiation between the corpuscle:- producing, and the hemal 
fluid conveying portions. 
Cuénot denies the existence of the radial heemal tracts, 
though he allows that there is a “glandular” tract in the 
radial septum; yet he figures (pl. iv, fig. 10) a tube dilated 
with its transparent colourless blood-fluid taken from that 
situation. What Cuénot describes as oblique septa in the 
radial periheemal tract simply appear to be the hemal tracts 
passing off to supply the sucker feet, &c. (vide Ludwig, 7). Of 
series of sections of the arm of Ophioglypha lacertosa, 
some sections show a well-marked hzmal radial strand with 
blood-fluid dilatation ; others might lead one to deny the exist- 
ence of the strand, so slight is it in size. Thus because at any 
one point no easily recognisable strand can be seen, we must 
look further before we conclude that it does not exist. 
The following is a summary of the functions carried on by 
the heemal system : 
1. Nutrient substances (proteids, &c.) absorbed from the gut 
are distributed in a state of solution to the various organs. 
2. Nutrient substances are distributed by means of ameeboid 
cells (in the young certainly, in the adult possibly) which use 
the strands of the system, as it were, like railway lines.! 
1 Cuénot (No. 3, p. 50, and No, 22) advances a theory that certain 
granules contained in “ amibocytes” consist of an “ albuminogenous”’ fer- 
meut, which has the power of converting dialysable into non-dialysable 
proteids, and thus prevent loss by osmosis ; he maintains that this ferment is 
to be found in all animals from Echinoderms to man. It is now well known 
that there is a considerable difference between osmosis through a dead, and 
