360 THE FLUIDS OF THE EGG. 



separates as a white, soft mass, which corresponds with Fremy's 

 cerebric or oleophosphoric acid: it also is neutral, contains 

 nitrogen and phosphorus, swells in water like starch, and fuses at 

 a high temperature : in its isolated state it is insoluble in ether, 

 dissolves readily in alcohol, and combines freely with metallic 

 oxides ; if it be again dissolved in spirit of wine, it loses phos- 

 phate of lime, and reddens litmus. 



We shall treat more fully of these substances when we consider 

 " the brain and spinal cord ;" and, in order to avoid unnecessary 

 repetition, we shall postpone to that chapter a notice of our own 

 experiments and observations. 



Two pigments were discovered by Chevreul in the yolk a 

 yellow and a red one ; both may be extracted with cold alcohol ; 

 the red one, which contains iron, is less readily soluble in ether 

 than the yellow one, in which that metal is not present : when 

 perfectly freed from fat, they appear to be all but insoluble in 

 ether ; neither of them has, however, been carefully examined. 



Whether the organic acid which occurs in the yolk is lactic 

 acid) is very doubtful ; at all events, its presence is by no means 

 established from the little that Gobley tells us on the subject. 



Although Gobley has convinced himself that the constituents 

 of the yolk which contain phosphorus are not in combination with 

 ammonia, he yet assumes that hydro chlorate of ammonia, to the 

 extent of 0*034^, is present in that fluid. 



With regard to the mineral substances, we find in the ash of 

 the yolk the ordinary salts of animal substances, but they occur in 

 very different proportions from those in which we ordinarily find 

 them. The compounds of potassium preponderate considerably 

 over those of sodium, and, according to Poleck,* the chlorides are 

 entirely absent ; but, on the other hand$ Rose and Weberf have 

 more recently found that, at all events, some chloride of sodium 

 (namely, 9*12^- of the inorganic matters) can be detected in the 

 yolk, if the organic matters have not been destroyed either by 

 carbonisation or by incineration. Only monobasic phosphates can 

 be discovered in the ash prepared according to Rose's method, 

 and in this Poleck found from 66*7 to 67'8-g- of phosphoric acid, 

 and Weber 70'92; a little peroxide of iron (]'45J of the ash), 

 and a small quantity of silica (0*5 5-g- of the ash) were also found 

 in the yolk-ash. If we call to mind the composition of the cor- 

 puscles, we cannot fail to be struck with the great analogy that 



* Pogg. Ann. Bd. 79, S. 155161. 

 t Ibid. p. 398 429. 



