ZOOLOQY AND BOTANY, MICROSCOPY, ETC. 551 



Albuminoid Constituents of WMte of Egg.*— MM. G. Corin and 

 E. Berard have investigated the albnmiaoid constituents of the white of 

 egg. They find that of those which are coagulable by heat two belong 

 to the class of globulins and three to that of true albumins ; the quan- 

 tity of peptones increases with the age of the egg. There is a colouring 

 matter which is not coagulated by heat, but is taken up by every 

 coagulation which occurs in it. The albumins strictly so-called have, 

 when made opalescent by an increase of temperature, a property which 

 has hitherto been supposed to be peculiar to globulins ; that, namely, of 

 being precipitated by sulphate of magnesia. It is possible that albumin, 

 just before coagulation, passes through a stage in which ifc has the 

 composition and properties of globulins. 



Embryochemical Investigations.! — Prof. L. Liebermann has inves- 

 tigated some of the less well known constituents of the egg of the fowl. 

 He finds that the germinal disc chiefly consists of albuminoid bodies, 

 belonging apparently to the globulin group ; there seem to be also 

 smaller quantities of lecithin or some similar substance. Few fatty 

 acids were found in the yolk. The fat of the egg consists of a mixture 

 of a solid and a fluid fat with some cholesterin. The firm fat consists 

 chiefly of tripalmitin with, probably, a very little stearine ; the fluid or 

 true oil of the egg is a glyceride. Both are much poorer in carbon than 

 other animal fats. The fat of fresh unhatched egg does not contain any 

 considerable quantity of free fatty acids, which are, however, developed 

 to a considerable extent during hatching. Fowls' eggs do not contain 

 any appreciable quantity of organic phosphates, — there is, however, a 

 relatively large quantity of calcium which probably exists in the form 

 of calcic albuminate; there is no direct evidence of the presence of 

 sulphates ; the quantity of chlorine is variable, but it is not certain on 

 what the variability depends. There may be other inorganic consti- 

 tuents, but, if so, their amount must be very small. The albumen of the 

 egg is capable of forming, in the presence of strong acids, phosphates 

 with the phosphoric acid, while, in the presence of dilute acids, soluble 

 organic phosphates are formed. 



In the second portion of the essay the metastasis of the egg while 

 being hatched is dealt with. The embryo itself always becomes richer 

 in mineral matters, fat, and albumen, but the dry substance of the whole 

 contents of the egg, taken as a whole, diminishes considerably ; the con- 

 siderable increase in the fat of the chick is not due to the formation of 

 fresh fat, but is chiefly dependent on the fact that what remains of the 

 nutrient yolk is taken up into the abdominal cavity of the chick. The 

 constituents of the egg are used up regularly during the period of 

 hatching ; the quantity of mineral matter remains almost unaltered. 

 Notwithstanding the taking up of oxygen, there is a loss in the amount 

 of that gas. The loss in weight suffered by the egg is obscured by the 

 evaporation of water ; the undeveloped egg loses more water than the 

 developed, and on the last day of hatching the ripe chick in the egg 

 contains more water than an equal quantity of unfertilized egg-matter. 

 The embryo uses up oxygen, of which a part only becomes carbonic 

 acid ; this indicates the formation of a fresh quantity of water. 



The special chemistry of the embryonic body is next dealt with. In 



* Bull. Acad. E. Sci. Belg., Ivii. (1888) pp. 643-62. 

 t Arch. f. d. Gesi^mmt. Physiol. (Pfliiger) xliii. (1888) pp. 71-151. 



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