PLYMOUTH MARINE BIOLOGICAL LABORATORY. 61 



Their very intimate association with chloropliyll, and the actual 

 change of that substance into them, which I have sometimes 

 observed, teach that the step from one to the other colouring 

 matter is not a great one. When we also consider that they are 

 widely distributed throughout the vegetable kingdom, it no longer 

 becomes difficult to understand why chlorophyll should be built up 

 by animals. I am quite convinced that Prof. Lankester's contention 

 that true animal chlorophyll exists can no longer be contradicted. 



Krukenberg* has shown that the lipochromes are connected 

 closely with the lipochromoids and melanoids, and through the 

 latter with the melanins ; if so, they furnish the radicals for the 

 construction of many black and brown pigments (such as we find in 

 Holothuria nigra, whose interior is, as said before, pigmented, to an 

 extraordinary degree, by lipochromes). 



The narrow view that all or nearly all the pigments of the 

 vertebrate body are formed from heemoglobin, held by many human 

 physiologists up to a very late period, is shown to be erroneous by a 

 study of the chromatology of the lower forms. Thus there are other 

 mother-substances such as the histohsematins, which are of as great 

 importance to many Invertebrates as hgemoglobin is to the higher 

 forms, and it is only by a knowledge of this fact that we can 

 explain the occasional occurrence of such pigments as haemato- 

 porphyrin in the integument of a starfish, in slugs, and in Solecurtus 

 strigillatiis,-\ as I have shown, or of biliverdin in Actinia mesemhryan- 

 themum, as I have also shown, or in the shells of various molluscs, 

 as Krukenberg has pointed out. J 



These histohaematins and others, such as the enterohaematin of 

 snails, slugs, the common limpet, the crayfish and Doris, actino- 

 haematin, and Lankester's chlorocruorin, may possibly, and probably 

 do, represent immature kinds of haemoglobin on their way, as it 

 were, to form that complex body, but they certainly are not meta- 

 bolites of hasmoglobin. 



The view that modified myohaematin from pigeon's muscle is 

 haemochromogen, which Herr Ludwig Levy holds, and endeavours to 

 prove in a recent paper,§ cannot be maintained by anyone who 

 extends his observations to invertebrate animals. Levy further states 

 that it is derived from haemoglobin, but where is the haemoglobin 

 from which it comes in a bee, a wasp, a butterfly, a slug, a snail, a 

 crayfish, or a lobster, or in many others in which not a single trace 

 of haemoglobin can be detected by the most careful spectroscopic 



* Ceutralb. f . d. medic. Wissensch., 1883, S. 785—788. 



t Jl. Physiol., loc.cit. 



J Centralb. f. d. medic. Wissensch., loe. cit. 



§ U ber den Farhstoff der Mu.ilceln, Inaug. Dissert. Strassburg, 1888. 



