CHAP. II.] THE BLOOD. 131 



the colouring matter of the blood of Planorbis, expressed in wave-lengths in 

 millionths of a millimetre. 



Centres of Bands. 



Normal oxy-haemoglobin 581 545 

 Planorbis 578 542-J. 



According to the measurements of Preyer and the Author, the position of 

 the bands in Planorbis as stated above really coincides almost exactly with 

 that of the bands of oxy-haemoglobin. 



It must not be concluded that all the red colouring matters found 

 in invertebrate animals are identical with haemoglobin. Thus the peri- 

 visceral cavity of Sipunculus nudus, which is abundant in the Gulf of 

 Naples, has a pale madder-like colour due to a large number of coloured 

 corpuscles, varying in size between -^--Vfrth and -^V^-th of an inch, in which 

 a pink colouring matter is deposited. This colouring matter, which is 

 found in other tissues of that creature, is quite distinct from haemoglobin 1 . 

 Whether certain crystals which are obtainable from the blood of insects 

 consist of haemoglobin or not has been disputed, and yet deserves further 

 investigation 2 . 



On the Green Blood of Certain Annelids. Chlorocruorin. 



In 1838 Milne Edwards 3 had discovered that in certain Annelids 

 of the genus Sabella, the blood possessed a green colour, and a 

 similar observation was made by M. de Quatrefages in the case of the 

 annelid Chloronema Edwardsi. Professor Ray Lankester 4 some years 

 ago shewed that the green colour is due to a body to which he gave 

 the name of CHLOROCRUOEIN. 



Lankester's researches were carried out on Sabella ventilabrum 

 and Siphonostoma. 



He found that the blood yielded an absorption spectrum with two 

 distinct bands, viz. one between C and D, and a second much less 

 distinct band in the green, almost midway between D and E. On 

 reducing a solution of the blood by means of one of the reagents 

 used with a similar object in the case of haemoglobin, Lankester 

 found that the two bands were replaced by a single band having nearly 

 the same position as the darker of the two, though fainter than it. 

 On agitating with air the two bands returned. 



The Author has reduced Professor Lankester's observations to a scale of 

 wave-lengths, and finds that the first band of oxy-chlorocruorin, as drawn 

 by Lankester, extends from wave-length 588 '5 to 617, its centre being, 

 therefore, 602*7. The second band extends from 560 to 570. The band 

 of (reduced) chlorocruorin extends from wave-length 588'5 to 611'3, and 

 its centre therefore corresponds to wave-length 600. 



1 Lankester, Op. cit., p. 80. 



2 Landois, Zeitschr. f. wiss. Zoologie, Vol. xiv. pp. 55 70, Plates vn. ix., 

 (quoted by Preyer, Op. cit. p. 10). The Author has not seen th'e original paper. 



3 Milne Edwards : " Eecherches pour servir a 1'histoire de la circulation chez les 

 Annelides." Ann. des Sciences Natur., 1838. 2 me aerie. Vol. x. p. 190. 



4 Lankester : Journal of Anatomy and Physiology, 1868, p. 114: ibid. 1870, p. 119. 



C) 2 



