IN VARIOUS PHYSIOLOGICAL CONDITIONS. 257 



Shell-snail (Helix pomatia) and that of certain Cephalopods (Loligo 

 and Eledone), as /well as of certain Tunicata (as, for instance, of 

 some Ascidians). 



The blood of the large Shell-snail contains, according to their 

 investigations, 8'398-g- of organic, and 6' 12 of mineral substances, 

 there being 0'033 of oxide of copper in the latter. This blood is 

 especially distinguished by assuming a blue colour on exposure to 

 the air, in consequence of the access of oxygen, and again becoming 

 colourless by the action of carbonic acid. Alcohol yields a colour- 

 less coagulum ; ammonia removes the blue colour, which is restored 

 by neutralization with hydrochloric acid. The blue pigment is 

 precipitated by alum and ammonia, and is entirely destroyed at 

 50. The blood of the Ascidians and Cephalopods presents the 

 opposite relations in regard to colour to that of the large Shell- snail. 

 It is not coloured blue either by oxygen or nitrogen, but carbonic 

 acid converts it into an intense blue. Oxygen does not cause the 

 entire disappearance of this colour; while ether and alcohol in- 

 stantly communicate a blue colour to the originally colourless 

 blood. Bibra found in this blood 4'7-jj- of organic and 2'63J of 

 mineral substances, but no iron, although some copper. 



I have made some experiments* on the blood of insects, and 

 especially of the lepidoptera in their larva state. On making an 

 incision into the skin of a caterpillar, on the abdomen, a transparent, 

 thick, pale yellowish green juice exudes, which under the micro- 

 scope discloses roundish cells without a distinct nucleus ; the cell- 

 walls appearing stippled like those of pus-corpuscles and having 

 a diameter varying from -3^'" to TTO"'- Dilute acetic acid does not 

 change the cells, but the concentrated acid dissolves them. 

 Caustic alkalies cause them to conglomerate into masses like most 

 cells and even the yeast-globules, making them appear some- 

 what relaxed in texture, distorted and granular, so that they 

 resemble granular cells. Hydrochlorate of ammonia does not 

 change them. Besides these cells, we very frequently observe 

 large roundish oval cells, having a distinct nucleus, and not unlike 

 many of the pavement epithelium cells. These are not changed 

 by acetic acid or the caustic alkalies. More rarely there occur 

 pyriform, or spindle-shaped, and other irregularly formed cells. 

 Fat-globules are always present in this fluid ; they might be 

 referred to the fat surrounding the stomach, if they did not likewise 

 occur in the fluid of the dorsal vessels. 



The intercellular fluid of the blood of insects assumes a dark 

 * Goschen's Jahresb. Bd. 2. S. 19. 



VOL. II. s 



