1891-92.] A. B. Griffiths on the Blood of the Inmrtebrata. 125 
The composition of the blood of these insects is represented in 
the next table : — 
Pontia 
hrassicoe. 
Noctua 
pronuha. 
Vanessa io. 
Smerinthus 
tilice. 
Lueanus 
cervus. 
Dytiscus 
diinidiatus. 
Water, 
88-49 
88-09 
87-94 
88-21 
88-29 
88-35 
Solids, 
11-51 
11-91 
12-06 
11-79 
11-71 
11-65 
J Proteids, &c.. 
7-89 
8-10 
8-08 
7-92 
8-20 
8-17 
\ Salts, 
3-62 
3-81 
3-98 
3-87 
3-51 
3-48 
Concerning the coagulation of the blood of insects, it may he 
stated that Poulton ^ has shown that the blood clots after a vari- 
able period of time; and he has known samples of blood that have 
not clotted at all. Larval blood coagulates far more rapidly than 
pupal blood. The author entirely confirms these observations of 
Poulton. 
The gases of the blood of the above-mentioned insects, investigated 
by the use of the mercurial air-pump, gave the following results : — 
Oxygen. 
Carbonic Anhydride. 
Nitrogen. 
Pontia hrassicoe, . 
16-34 
34-21 
1-92 
Noctua pronuha, . 
17-24 
33-19 
1-72 
Vanessa io, . 
16-56 
34-00 
1-81 
Smerinthus tilice. 
17-10 
33-09 
1-76 
Lueanus cervus, . 
16-28 
34-97 
2-31 
Dytiscus dimidiatus. 
16-22 
34-86 
2-35 
The above figures (the averages of two determinations in each 
case) represent volumes of the gases per 100 volumes of blood (the 
volumes being reduced to 0° C. and 760 mm.). Although the blood 
of the Lepidoptera appears to be devoid of respiratory pigments, it 
has a respiratory function. In fact, the want of respiratory pig- 
ments in this case confirms the idea that the mere colour of haemo- 
globin, for example, is of no use. It may be remarked, however, 
that myohaematin f (which is connected with haemoglobin and its 
derivatives) occurs in the muscles of insects ; and tissue-respira- 
* Ptoc. Roy. Soc. Lond., 1885, p. 294. 
t MacMunn, Phil. Trans., 1886, pt. i. p. 272. 
