42 THE ROYAL SOCIETY OF CANADA 



out by Grund'^ on the ox. The conclusion is drawn by this author 

 that the amount of pentose present is proportional to the richness of 

 the organ in nuclear substance. The present writer found that the 

 relation between the pentose content of various organs of the dog- 

 fish (Squalus sucklii) is similar to that found by Grund for the ox, 

 but that the absolute amounts present are somewhat greater in the 

 former case.^ 



For some time past determinations of pentose in various tissues 

 of marine animals have been made as opportunity offered. The 

 main object has been to find a suitable raw material from which to 

 prepare the pentose compounds for closer characterization, but the 

 results obtained seem worth considering in their bearing on the 

 question of the relation between the quantity of these compounds 

 present and the richness of the tissues in nuclei. They are also of 

 some interest from the general standpoint of comparative bio-chem- 

 istry since few determinations of pentose in the tissues of marine 

 animals have hitherto been published. 



Methods 



The organs examined were taken from freshly killed animals. 

 In all cases except that of the mud shark, of which only one specimen 

 was available, they were taken from several animals and samples 

 drawn from the mixed material for analysis. The organs were cut 

 into small pieces and brought rapidly into alcohol. After standing a 

 few days the material was finely minced and kept in alcohol, which 

 was changed at intervals, until dehydrated as far as possible. It was 

 then pressed, dried at air temperature, finely ground, sieved, ex- 

 haustively extracted with ether, and again air dried. In this way 

 material free from most of the connective tissue and containing about 

 10 per cent, of moisture was obtained. The figures quoted have been 

 calculated to the material dried to constant weight at 100°C. 



The determinations were made on the air-dried material direct 

 by the method of Tollens and Krobe as modified by Grund and the 

 results calculated as xylose. They cannot, therefore, be taken as an 

 absolute measure of the amount of pentose present since this is 

 unquestionably mainly derived from nucleotides whose pentose con- 

 stituent has been shown by Levene and Jacobs^ to be (i-ribose and, 



3Grund, G., Zeit. Physiol. Chem., 1902, XXXV, 111. 



^Berkeley, C, Journ. Biol. Chem., 1920, XLI, p. liv. These determinations 

 have been requoted in this paper for comparison with the other figures given. 

 ^Levene, P. A., and Jacobs, W. A., Ber. Chem. Ces., 1909, XLII, 3247. 



