118 Proceedings of Royal Society of Edinbiirgli. [sess. 
Echinoderms, MacMimn* has found hEematoporphyrin, which is 
well known to be a decomposition product of haemoglobin ; and 
there is no doubt that tissue-respiration plays an important part in 
the respiration of these animals. Although echinochrome and 
haemoglobin have been found in the blood of some of these animals, 
the blood of others has no respiratory function. 
We now consider the composition of the saline matter contained 
in the blood of the following Echinoderms : — Spatangus, Echinus, 
Uraster, and Solaster. The percentages of saline matter contained 
in the blood of these animals have been ascertained by the author, 
as follows : — 
I. 
IL 
III. 
IV. 
Y. 
Average. 
Spatangus, 
1-820 
1-834 
1-862 
1-841 
1-836 
1-832 
Echinus, 
1-786 
1-752 
1-761 
1-706 
1-772 
1-755 
Uraster, 
1-924 
1-936 
1-922 
1-941 
1-932 
1 -931 
Solaster, 
1-973 
1-962 
1-983 
1-985 
1-968 
1-974 
The author has also submitted to analysis the ashes of the blood 
of these animals. The ashes were obtained by incinerating the 
blood, partially covered in a platinum dish, at a very low tempera- 
ture. By so doing the alkaline metals are not volatilised as they 
are when a high temperature is used. 
The following results represent the averages of three analyses in 
each case 
Spatangus. 
Echinus. 
Uraster. 
Solaster. 
Iron oxide (Fe203), . 
trace. 
trace. 
trace. 
trace. 
Lime (CaO), . . 
3-62 
3-78 
3-02 
3-16 
Magnesia (MgO), 
1-05 
1-12 
1-38 
1-36 
Potash (K2O), . 
4-81 
4-76 
4-52 
4-63 
Soda (Na20), . 
43-78 
43-82 
44-22 
44-03 
Phosphorie acid (P2O.5), 
4-62 
4-53 
4-24 
4-32 
Sulplmric acid (SO3), 
2-31 
2-36 
2-22 
2-23 
Chlorine, .... 
39-81 
39-63 
40-40 
40-22 
100-00 
100-00 
100-00 
100-00 
* Jour. Phys,, vol. vii. p. 240. 
