248 



Dr. C. A. MacMunn. Researches on [Nov. 26, 



a mass of indifferent tissue, into which pass representatives of all 

 three germinal layers. This must represent the primitive streak. 



The persistence of the blastopore to form the anus has been demon- 

 strated in the Amphibia, by Miss Johnson in the Newt, by Gasser in 

 Alytes, and by Spencer in the Frog. The fact that it persists in the 

 Cyclostomata appears to point to the fact that this is a primitive 

 feature retained in those eggs which have not become much modified 

 by the presence of a large mass of yolk. This view would be greatly 

 confirmed if renewed observation on the development of Amphioxus 

 should demonstrate the same fact. 



III. " Researches on Myohaimatin and the Histohsematins." By 

 C. A. MacMunn, M.A.. M.D. Communicated by Professor 

 M. Foster, Sec. U.S. Received October 19, 1885. 



(Abstract.) 



This paper contains an account of observations made on the spectra 

 of the organs and tissues of invertebrates and vertebrates, which 

 have brought to light the presence of a series of animal colouring 

 matters which had not previously been discovered. 



The name histohae matins is proposed for all these colouring matters, 

 and that of myoheematin for the intrinsic pigment occurring in 

 striped muscle, which belongs to the same series. 



These pigments are not identical with any known decomposition 

 product of haemoglobin, and they are found in animals in whose 

 bodies no ha3moglobin can be found. 



The method of examination is as follows : — The tissue or part of 

 organ to be examined is put into a compressorium, by means of which 

 any required thickness can be obtained, it is illuminated by means of 

 a large sub-stage condenser, and examined with a Sorby's microspec- 

 troscope fitted to a binocular microscope, the binocular form being 

 preferred, as one tube is free for the observation of the specimen. 

 The source of illumination was generally an argand gas burner, some- 

 times direct sunlight, sometimes a Swan lamp. The objectives of the 

 microscope up to the one-eighth were so adapted as to enable both 

 fields of the microscope to be fully illuminated, which is a matter of 

 importance in dealing with small quantities of material, or in differ- 

 entiating those portions of an object which give different spectra. 



The Histohcp.matins. — Examined in this way the organs and tissues 

 of invertebrates and vertebrates present a series of spectra, which are 

 all evidently connected with each, other. From Echinoderms to man 

 the same appearances have been found ; thus there is a most striking 



