48 INANITION AND MALNUTRITION 



ment of the sea-urchin and the starfish. A few observations have also been 

 made upon general (total ) inanition in these forms. 



Echinoidea. — The effects of calcium deficiency upon the development of the 

 sea-urchin were studied first by Pouchet andChabry ('89, '89a, '89b), who reared 

 the larvae in sea- water from which a part or all of the calcium had been removed 

 by precipitation with sodium or potassium oxalate. In media with about nine- 

 tenths of the calcium remaining, the development appears normal up to about 40 

 hours. "Mais, a la 60 heure, elles sont encore a l'etat de gastrula, tandis que 

 les temoins ont des spicules ramifies et un intestin complet. Apres 90 heures 

 ces larves, sans prendre des spicules, entrent dans une veritable phase pluteus, 

 caracterisee pour elles par le differenciation de l'intestin en trois regions: 

 oesophage, estomac et rectum. Mais la forme generate reste spherique, sans 

 prolongements, et la mort survient apres quelques jours d'existence en cet etat. 



"En poursuivant une elimination plus complete de la chaux, les larves ne 

 depassent plus le stade gastrula et meme le nombre de cellules qui l'atteignent 

 devient de moins en moins grand. Lorsqu'on reste, au contraire, en deca de la 

 quantite que nous avons indiquee, le developpement des spicules est simple- 

 ment retarde, et ils subissent en outre, une deformation variable. Sur quelques 

 larves, on observe la formation d'un appendice probosciforme, median, et 

 qui semble tenir la place des deux prolongements anterieurs frontaux, sans 

 spicule interne." Thus calcium deficiency results in retarded and abnormal 

 development, especially in the skeletal system. 



The necessity and significance of the various salts in development was 

 further revealed by the brilliant investigations of Herbst ('97). In artificial 

 sea-water of varied composition he studied the effects of various deficiencies at 

 various stages in the development of numerous organisms. He used chiefly 

 sea-urchin and starfish, but made incidental observations upon several other 

 invertebrates (also the fish Labrax lupus). The salt mixtures used contained 

 various combinations and proportions of NaCl, KC1, MgSo 4 , MgCl 2 , CaS0 4 , 

 CaCo 3 , Ca 3 P20 8 and FeCl 3 . Chemically pure salts were found desirable, since 

 in some cases {e.g., iron), mere traces appear notably to affect the results. 



In the sea-urchin {Sphaer echinus granulans and Echinus microtuberculatus) , 

 the results may be summarized as follows: In phosphorus-free solutions, the 

 segmentation of the fertilized ova is abnormal and soon arrested (Fig. 17). 

 Experiments beginning with later stages (blastula, gastrula or pluteus) like- 

 wise resulted in prompt arrest of development and rapid death of the organisms. 

 In sulphur -free solutions, the fertilized ova undergo retarded development, 

 which proceeds only up to the formation of abnormal gastrulae (Fig. 18). 

 Experiments beginning with later stages (blastula, gastrula or pluteus) resulted 

 in death without further development. Chlorine and potassium (Fig. 24) were 

 similarly found essential for segmentation, and also for continued development 

 beginning at the later stages. In magnesium -free solutions the fertilized ova 

 show no apparent difference from controls up to the gastrula stage (second day), 

 but thereafter become retarded in development, not exceeding an abnormal 

 pluteus stage with imperfect skeleton (Fig. 20). Magnesium was found essen- 

 tial also for development in experiments beginning with later stages. Calcium 



