326 SERGIUS MORGULIS 



work forms the starting point of a series of researches which have 

 thrown light upon the problem of animal growth. 



The role of water in the processes of growth was first definitely- 

 appreciated by botanists. An analysis of the water content in 

 Heterocentron at different levels of the stem, for instance, re- 

 vealed that, while at the tips there is 73 per cent of water, the 

 amount of water increases suddenly in the first internode to 88 

 per cent, and in the second internode reaches a maximum of 93 

 per cent, and that in the following internodes the per cent of 

 water commences to fall off. Davenport ('97), inspired by the 

 results of botanists, extended the investigation of the change of 

 the water content during growth to animals. He used for that 

 purpose frog embryos, studying the water content at different 

 stages by the ordinary method of dessication, and found that 

 twenty-four hours after hatching the per cent of water was 56, 

 that the percentage of water increased steadily up to the four- 

 teenth day after hatching, when the maximum (96 per cent) was 

 reached, and that it then began to diminish, being only 88 per cent 

 eighty-four days after hatching. These results are graphically 

 represented in fig. 4, which is reproduced from Davenport's 

 original paper. It shows that very rapid increase of the quantity 

 of water, followed by a slow but continuous fall in the water con- 

 tent as one passes from the earlier to the more advanced stages 

 of development. 



While this investigation of Davenport, emphasizing the role of 

 water, has helped greatly to further the study of growth, and in 

 fact has evoked several very important contributions from other 

 students, it may nevertheless be pointed out that the discovery 

 in young embryos of a greater water content than in old ones had 

 been already demonstrated by Bezold ('57) for a number of ani- 

 mals, including the amphibians. Bezold (p. 523) says ''Die 

 Entwicklung und das Wachsthum eines jeden Thieres ist durch ge- 

 wisse, fiir die Art oder Gattung desselben typische Veranderungen 

 in dieser Zusammensetzung (aus Wasser, organischer Materie 

 und anorganischen Salzen) charakterisiert .... Die 

 Hauptmomente dieser Veranderungen sind: a) Abnahme im 

 Gehalte des Organismus an Wasser und fliichtigen Bestandtheilen 



