Miscellaneous. 73 



recentlj' made by Dr. A. KorotnefF of Moscow *, which he considered 

 erroneous in so far as they indicate the presence of a huge amoeboid 

 cell or Plasmodium, in the oesophagus and stomach of Salpa, func- 

 tioning as a digestive organ. Dr. KorotnefF describes this cell as 

 arising from the repeated division of a single cell which early in 

 the life-history of the animal is separated from the intestinal wall. 

 This giant cell or plasmodium, acting like a huge rhizopod, carries 

 on a form of parenchymatous digestion of the food taken by the 

 animal, passiiig the resulting chyle into the walls of the intestine by 

 means of its pseudopodia. Now by reference to an article by 

 Metschnikoff " On Intracellular Digestion in Invertebrates " (in the 

 ' Quarterly Journal of Microscopical Science' for January 1884), it 

 will be seen that such a form as Korotneff describes has never been 

 met with, and his description stands alone and anomalous, both as 

 regards the situation and size of the digestive plasmodium and as to 

 the method of its formation, for in all cases in which such struc- 

 tures have been found in Invertebrates they have always arisen by 

 the fusion of separate cells, not from the repeated division of one cell. 

 In a large number of series of sections made by the new "ribbon " 

 method, the speaker was not only unable to find " the lumen oblite- 

 rated " by the peculiar structure of tho wall of the intestine de- 

 scribed by Korotneff, but in a model of the visceral nucleus made 

 after Born's " Plattenmodellirmethode " the lumen of the entire 

 intestinal canal is shown to be completely free throughout. He 

 did, however, get sections which gave pictures almost identical with 

 those portrayed by Korotneff, i. e. the lumen filled with what he 

 describes as a large nucleated granular cell, containing various food- 

 particles, and he could trace this so-called " cell," not only back 

 into " the 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. He accounts for it as follows :— 

 The endostyle of Salpa has been very carefully studied by Hermann 

 Fol, 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, when it acts as a means for catching the food-particles from the 

 ingurgitated water. Ey the action of 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 a continua- 

 tion of the aforesaid bordering bands through the oesophagus into 

 the stomach. Now in studying a series of sections of a Salpa which 

 had had abundant food, we found as w^e approached the oesophagus a 

 mass of material answering to the description of Korotneff's " rhizo- 

 pod." It takes staining readily and may be traced backward into 



* " Ueber die Knospuug der Anchinia,^' in Zeitschr. f. wiss. Zoologie, 

 Bd. 40, Hft. i. (1884). 



Ann. & Mag. N. Hist. Ser. 5. Vol. xiv. 6 



