707 
arisen by the fusion of separate cells, not from the repeated division 
of one cell?. 
The oesophageal Amoeba of Korotneff, however, originates »by 
the separation of a single cell, which later subdivides itself« with as 
little precedence for so doing as it has for its unique size and position. 
After reading the preliminary mention which Korotneff gave of this 
peculiar structure in Salpa®, I made a number of series of sections, 
according to the ribbon method, for the special purpose of finding it. 
While I failed in this, I found the structure of the walls of the stomach 
and oesophagus as described by him, in so far as the epithelial cells of 
one side » being cylindrical and beset with cilia«, while on the other 
side the cells were more definitely outlined near the basal membrane, 
than toward the lumen of the digestive cavity, but nowhere did I find 
»the lumen obliterated« by these cells, and nowhere did I find them 
completely losing their individuality and forming a true plasmodium. 
I made moreover a model of the visceral nucleus after Born’s ‘platten- 
modellirmethode‘4, in which the lumen of the oesophagus is shown to 
be completely free throughout. I did however get sections which gave 
pictures , almost identical with those portrayed by Korotneff, i. e. 
the lumen is filled up, with what he describes as a huge nucleated 
eranular cell containing various food particles. Now I could trace this 
so-called cell, not only back into »that portion of the intestine lying 
next to the stomach« but through the rectum into the cloacal chamber, 
and through the oesophagus into the branchial sac, and I account for 
it as follows. The endostyle of Sa/pa has been very carefully studied 
by Herman Fol5 who demonstrated by means of carmine suspended 
in water, that it threw out a constant stream of mucus, when excited 
by the presence of nutritive material in the same water, with a reflex 
action like a salivary gland. The mucus is by an arrangement of cilia, 
spread out like a curtain over the inner surface of the branchial sac, 
where it acts as a means of catching the food particles of the ingurgi- 
tated water. By the action of the ciliary bands bordering the groove 
of the endostyle, the mucus is swept towards the oesophagus, and as 
it approaches this it is, by means of the stiff cilia on the sides of the 
gill, twisted into a thread and carried by the continuation of the afore- 
said bordering bands through the oesophagus and into the stomach. 
2 Metschnikoff, On Intracellular Digestion in Invertebrates. in: Quart. 
Journ. Microsc. Soc. Jan’y 1884. 
3 Zoologischer Anzeiger No. 148. VI. Jahrg. p. 483—487.° 
4 Archiv f. Micr. Anat. 12. Bd. p. 584. 1883. Also Amer. Naturalist. April 
1884. 
5 Über die Schleimdrüse oder den Endostyl der Tunicaten. in: Morphol. Jahrb 
1. Bd. 1876. 
