122 ANATOMY AND LIFE HISTORY OF MOLLUSCA. 



both species had a tendency, he remarked probably for the first 

 time, to shoot out into amaeboid processes. Many other observations 

 have been made, but it will be sufficient now to refer to those of 

 Mr. Ray Lankester " On the Distribution of Haemoglobin in the 

 Animal Kingdom," read before the Royal Society of London,* 

 and the researches of Dr. MacMunn.f Without detailing all the 

 observations, what refers to this subject may be summarized 

 as follows. 



The colour of the blood in invertebrate animals does not belong 

 to the corpuscles, but to the liquor sanguinis ; but there are 

 many exceptions. The color itself is blue after exposure to the 

 air, due to the presence of a pigment named haemocyanin, in most 

 cases. On analysis the blood is found to contain traces of copper 

 and iron. Extensive examinations have been made as to the 

 nature of this blood and its coloring matter, particularly in the 

 case of fresh-water mussels, snails (Helix pomatia, L., Lymncm 

 staynalis, Drap., and Paludina vivipara, Lam. J. &c. Most of these 

 animals have blue blood ; though in some this quality does not 

 appear until after exposure. 



Dr. Lankester has made special researches on the subject of 

 haemoglobin in Molluscan blood. He found that it occurred in 

 special corpuscles : — 1. In the blood of Solen legumen, where it is 

 diffused in a vascular or ambient liquid. 2. In the general 

 blood-system of the pulmonate Planorbis. 3. In the muscles of 

 the pharynx and jaws of certain Gastropods, observed in Lymncea, 

 Paludina, Littorina, Patella, Chiton, and Aplysia. Also in the 

 pharyngeal gizzard of Aplysia, being entirely absent from the 

 muscular and other tissues and the blood. 



Dr. Lankester found in his investigations amongst Mollusca, 

 that there were many cases of red tissue or liquid in the foot and 

 mantle, and in their nerve ganglia, which might be supposed to 

 be due to haemoglobin, but are not so, as the tissue or liquid did 

 not give the characteristic bands of haemoglobin when examined 

 by the spectroscope. The result of all his investigations was that 

 haemoglobin was found distributed irregularly throughout the 

 animal kingdom, being absent entirely only from the lowest 

 groups. It may occur in corpuscles of the blood or in the liquor 

 sanguinis, in muscular tissue or in nerve tissue. It may be 

 present in one small group of muscles, and absent from all the 

 rest of the tissues of the body. He thought that a partial 

 explanation of this arbitrary distribution may be found by 

 reference to the chemical activity of haemoglobin. Wherever 

 increased facilities for oxidation are requisite, haemoglobin may 



* Yol. xxi., No. 469. 



f " On the Chroniatology of the Blood of some Invertebrates/' Quart. 

 Journ. Micros. Science, Vol. xxv., 1885,, p. 469. 



