21)6 
CIRCrLATORY SYSTEM — AMCEBOCYTES. 
Ki(,. .Vn 7- — lUooil 
orpiiscics or anuubocytcs i)f 
Helix foniitia L., fixed wiili osniic acid, liigldy 
iiuignifictl (after N’ogi and Wing). 
same active respiratory substance is found abundantly in the blood 
of adult rianorbes, but not confined within special corpuscles, as in 
man or in the molluscan genera Sokii, etc., hut diffused through the 
circulatory iluid, to whicli it gives a bright pink appearance; this 
s])ecial abundance of haunoglobin in PI((iiorbis may be considered to 
be in direct correlation with the transitional character of their respira- 
tory .system and the feebly oxygenated state of the stagnant pools in 
which they so often live. 
The Amcebocytes ((tpeZ/^io, to change ; kvtos, a cell) or white blood 
corpuscles, known also as Phagocytes, are minute, indistinctly 
nucleated, unicellular organisms 
of variable size, resembling 
those of man in structure and 
exhibiting the same ama'boid 
movements. They possess vari- 
ous assimilating and nutrient 
functions and contain more 
oi- less abundant refractive 
albumonogenousgTanule.s,'\vho.se 
])rotoplasm is believed to serve 
as a sturehduse for the accumulation of fat and albuminoids and to 
form tbe means ready for the re])air of wounded tissue. 
The Ammbocytes seem from their origin to he connective tissue 
cells e.s])ecially adapted to live in an albnminous medium and are 
numerously pre.sent in the blood ; they originate on the walls of the 
lymphatic glands and arc reproduced hy direct divi.sion, ami possess 
a smooth diaiihauous outer membrane and a nodally thickened reticu- 
lated framework, with a more unstahle material iu the meshes. 
Tbe Pulsations {pulxo, I beat) or rhythmical contractions of the 
Ventricle of the heart furnish by their number a reliable index to the 
activity of the circulation, and in certain species of Gastropods are 
visible througb tbe base of tbe last whorl of the shell, and in some 
delicately shelled Pelecypods perceptible near the umhones. 
'I’he alternate contractions and relaxations of the heart are so 
persistent that they have been observed to continue for some time 
after its removal from the l)ody of the animal and when completely 
drained of blood ; according to Lister, the pulsations will recommence 
even twelve hours after excision if the (jrgan be moistened with blood. 
The activity of the circulation is, however, intluenced by many 
