Note on the Proteins of the Blood of Limulus Pol Yphemus L

The blood of Limulus polyphemus L. has been shown to contain the protein haemocyanin and white corpuscles. The blood clots with great rapidity. Loebl found that clotting is not preventable by the usual chemical methods but only by methods which prevent agglutination of the corpuscles. Further, Loeb has shown that the clot is formed by the agglutination of the corpuscles, indicating the absence of fibrinogen in the blood. By a study of the composition of the clot Alsberg and Clark2 showed that the clot contains no fibrin, but is composed mainly of a protein, the analysis of which showed C : S : N ratios more like those of glutins than fibrins. The nitrogen content of the clot protein was found to be 15.6 per cent. Haemocyanin, which remains in the serum, contains 16.8 per cent of nitrogen. This serum has a specific gravity of 1.040 as found by Gotch and Laws.3 They first studied the haemocyanin of Limulus and concluded that heating the serum does not completely coagulate the haemocyanin, because the liquid still remains blue after boiling. Howell4 states that in order to produce complete coagulation it is necessary to heat the