Grafted and multiple embryos. 



37 



of water is necessary to get 99 per cent, reduction with a spore 

 former in six hours, while 0.5 part to 1,000,000 is sufficient 

 for this degree of reduction with non-spore formers. 



4. Sixteen parts of available chlorin per million of water does 

 not effect complete killing of B. subtilis; 1.5 parts brings about com- 

 plete sterilization with B. coli and B. prodigiosus. 



26 (635) 

 Studies on barium feeding. 



By C. L. ALSBERG and 0. F. BLACK. 



[From the Office of Drug Plant, Poisonous Plant, Physiological 

 and Fermentation Investigations, Bureau of Plant Industry, 



Department of Agriculture, Washington, D. C] 

 Half-grown rats fed for some months on a mixed diet to which 

 BaS0 4 was added remained in good health and did not store up 

 measurable traces of barium in their tissues. However, when 

 instead of a mixed diet one poor in calcium was fed, other condi- 

 tions being the same, a few milligrams of barium were stored 

 in the tissue of each animal. It is therefore evident that under 

 special conditions even very insoluble substances may be absorbed 

 to some extent. 



27 (636) 



The production of grafted and multiple embryos. 

 By A. J. GOLDFARB. 



[From the College of the City of New York.] 

 After removing the fertilization membranes of sea urchin 

 eggs (Arbacea) and allowing them to develop to the desired stage, 

 the eggs were placed in an alkaline (NaOH) sea water and centri- 

 fuged in narrow bore tubes. In this way large numbers of eggs 

 were agglutinated, and developed into double, triple, etc., blas- 

 tulffi, gastrulae and plutei. In ten to forty per cent, the eggs and 

 blastomeres were more or less completely fused, forming giant 

 blastulae, composed of three, four or more eggs. 



In the first group parallel development took place, resulting 

 in double, triple, etc., embryos, many of which were subsequently 

 separated by the antagonistic sweep of the cilia. In the second 

 group, the eggs were more intimately united to form a common 



