APPENDIX. 



I. The Composition op H^mocyanin. 



The author* has ascertained the approximate composition of 

 hsemocyanin (see Tp. 142 etseq.). The hsemocyanin derived from the 

 hlood of Eoma/rus, Sepia, and Cancer respectively was submitted, 

 after purification, to chemical analysis. The percentage composi- 

 tion of this important substance is very constant. In this respect 

 it differs from haemoglobin. We are, therefore, justified in calcu- 

 lating an empirical formula for hsemocyanin as follows : — 



The blood of the lower, and some of the higher, Invertebrates is 

 a watery fluid, called the hydrolymph. But in the majority of 

 the higher Invertebrates, the blood is less watery and much richer 

 in albuminoids ; it is sometimes termed a hsemolymph. 



II. Invbetebrate Cartilage. 



Invertebrate cartilage is very similar, chemically and histo- 

 logically, to that of the Veriebrata. Dr. W. D. Halliburton f has 

 recently examined the head cartilage of Sepia, and the entosternite 

 of Limulus. " The basis in both structures is chrondrin ; there 

 is, however, in addition, a certain proportion of chitin, in the case 



* Comptes Sendus de I'Acad^mie des Sciences, tome 1 14, p. 496. 

 t Proceedings of Boyal Society, vol. 38 ; and Quart. Jour. Micro. Science, 

 vol. 25. 



