150 BEPOET— 1887. 



incubator at 36° C. for six hours. The pieces of glauci were then filtered 

 off, and the filtrate saturated with ammonium sulphate; the precipitate so 

 produced was collected on a filter. The filtrate contained abundance of 

 peptone, and the precipitate contained a small amount of deutero-albumose ; 

 the action having presumably been sufficiently great, so that digestion had 

 advanced beyond the proto-albumose stage. 



6. The mucin-like pruteid. — This proteid, which was first described by 

 Miescher in the protoplasm of pus cells, is also present in the cells of 

 lymphatic glands. It forms, in fact, the largest proteid constituent of 

 those cells. When the cells are extracted with a five- or ten per cent, 

 solution of either sodium chloride or magnesium sulphate, the result is a 

 slimy mass, very much resembling mucus in its appearance. It may be 

 obtained free from other proteids by pouring this mixture into a large 

 excess of distilled water; this peculiar proteid then extends in cohesive 

 strings throughout the water, and in time these contract and settle at 

 the bottom of the water. This is then washed by decantation with 

 I per cent, sodium chloride solution, in which it is very slightly soluble. 



The following are its chief properties : — 



(a) It is insoluble in water. 



(b) It is slightly soluble in | per cent, sodium chloride solution. If 

 the lymph-cells be extracted with this solution, a small amount of all the 

 proteids described goes into solution, and among them this one. Such an 

 extract is not, however, slimy ; it becomes slimy when the proportion of 

 salt is increased to a strength of 5 per cent. 



(c) When a 10 per cent, sodium chloride solution, with this proteid in 

 suspension, is heated to 50° C. the mucns-like strings shrink, and can 

 be easily filtered off. In the case of sodium sulphate extracts of glands 

 it is apparently carried down with the cell-globulin a, which coagulates 

 at this temperature. When the sodium chloride solution is boiled, the 

 shrunken flakes which formed at 50° C. break up and dissolve ; they are 

 not, however, reprecipitated on cooling. It is, however, precipitated once 

 more when poured into water, and also by the addition of acetic acid. 



(cl) Saturation with neutral salts. Saturation of a sodium sulphate 

 extract of cells with sodium sulphate causes little or no precipitation of 

 the proteids contained therein ; nor does it cause any mucinous appear- 

 ance. In a very weak sodium chloride solution (j per cent.), there is 

 also no mucin-like appearance ; this only comes on when the strength of 

 the solution reaches 5 per cent. ; saturation with sodium chloride causes 

 a small amount of shrinkage of this proteid, and renders filtration easier. 

 Magnesium sulphate acts in a similar way. Ammonium sulphate acts 

 similarly ; saturation with this salt, however, causes the proteid to lose 

 almost altogether its resemblance to mucin, and precipitates it as whitish 

 flakes. 



(e) It is precipitable by absolute alcohol, by basic lead acetate, by 

 dilute sulphuric acid, and by solution of tannin. 



(/) It is precipitated by acetic acid in strings like mucin ; like mucin 

 it is also soluble in baryta or lime-water ; from which solution it is again 

 precipitable by acetic acid, and not soluble in modei-ate excess of that 

 reagent. 



It is thus seen that this substance is very like mucin in its reactions, 

 and in its physical characters. The question arises : Is it mucin ? The 

 substance nuclein, of which the cell-nuclei are made up, has been described 

 as very similar to mucin ; but it is not this substance with which we have 



