126 
Proceedings of Royal Soeiety of Edinturgh. [sess. 
tion by means of this pigment is well developed in this class of 
animals. 
It appears that in the Lepidoptera the transport of oxygen from 
the surrounding medium to the living tissues is made, to a considerable 
extent, by means of colourless proteids of the blood. These sub- 
stances form 03 iygenised combinations which are unstable, and 
which are carried by the blood across the tissues and are there 
dissociated, yielding the oxygen to the elements of those tissues 
which require it. 
The Blood of Arachnids. 
The author has only ascertained the composition of the ashes of 
the blood of a few of these Invertebrates. These ashes gave the 
following results (the averages of two analyses in each case) : — 
Epdra. 
Tegenaria. 
Pholcus. 
Copper oxide (CuO), 
0-20 
0-23 
0-26 
Lime (CaO), .... 
3-56 
3-62 
3-50 
Magnesia (MgO), . 
1*94 
2-03 
1-98 
Potash (KgO), 
5-00 
4-91 
4-89 
Soda (Na^O), .... 
44-12 
44-63 
43-92 
Phosphoric acid (P 20 g), . 
4-83 
4-92 
4-85 
Sulphuric acid (SO 3 ), 
2-82 
2-78 
2-80 
Chlorine, .... 
37-53 
36-88 
37^80 
100-00 
100-00 
100-00 
The blood of these animals contains hsemocyanin, which is the 
well-known respiratory pigment containing copper. 
Lankester* has also shown that the blood of Scorpio becomes 
blue on exposure to air, and that it contains hsemocyanin. 
Myohsematin is present in the muscular tissues of the Arachnida. 
Concerning the uses of these two pigments, it may be stated 
that the haemocyanin receives oxygen from the air, and carries it to 
the tissues ; and the myohaematin receives the oxygen from the 
blood, and retains it until the tissue elements are in need of it. 
* Quart, Jour, of Micr. Sci., vol. xxiv. p. 151. 
