266 COLLOIDS IN BIOLOGY AND MEDICINE 



ing to H. GERHARTZ, there seems to be a very great shrinking even 

 of the albumin. For man he calculates the proportion of albumin 

 to water to be: 



Newborn 1 albumin, 5.6 water 



Adult 1 albumin, 4.3 water 



J. A. KUBOWITSCH has shown that the water content of a mam- 

 malian embryo's muscle sinks from 99.4 per cent to 8 per cent at the 

 termination of fetal life and finally to 75-80 per cent in adults. 

 According to L. B. MENDEL and LEAVENWORTH, pig's liver has a 

 quite constant water content of about 80 per cent during fetal life 

 but diminishes to 67.3 per cent in the adult. 



From this we understand that in the earliest stages, growth only 

 results by means of the water taken up through swelling, though a 

 time comes when growth is induced by the entrance of solid sub- 

 stances, by assimilation. This assimilated substance meanwhile 

 binds less water; with further growth there is associated a relative 

 shrinking which after reaching its maximum (growth) passes with 

 further age into an absolute shrinking. 



According to MUHLMANN, aging of different organs does not 

 proceed equally. The weight of human intestines increases up to 

 the fiftieth year, but the heart and lungs never cease gaining weight; 

 the brain, on the other hand, has achieved its maximum weight at 

 about the end of the second decade and from then on it gradually 

 declines. The brain also shows definite microscopic aging phenom- 

 ena, even in the earliest years. Lipoid pigment granules appear 

 in the nerve cells which continually increase and at an advanced age 

 fill the entire cell According to MARINESCO it is much easier to 

 destroy with solvents suspensions of ganglion cells of a newborn 

 puppy than an old dog. As the result of his studies of pigment 

 granules in nerve cells he also arrives at the conclusion that aging is 

 due to the coagulation of physiological elements, a diminution of 

 surface tension, such as we know occurs in the aging of colloids 

 (see p. 73). 



H. SCHADE determined that the subcutaneous connective tissue dis- 

 solved much more rapidly in NaOH when it was derived from a month 

 old child than when it was taken from a thirty-two year old woman. 



F. TANGL* is of the opinion that the shrinking of the animal 

 organism during embryonal development is a duplication of the 

 same phylogenetic process and shows by numerous tables that the 

 lower invertebrates, even those which do not live in water, are 

 usually more rich in water than the higher vertebrates. 



By what chemism increase of water and substance are condi- 



