EFFECT OF EXTRACT OF THYROID GLAND 



6 9 



a minute trace of HN0 3 to the water, the bubbling hitherto 

 arrested is renewed with extraordinary vigour. 



Effect of Extract of Thyroid Gland 



I investigated the effect of many other substances on 

 photosynthetic activity, of which I will give several instances. 

 The first section of Table XII. gives the results obtained 

 with dilute extract of thyroid gland. In specimen III. 

 a dilution of one part in a billion produced a maximum 

 increase of activity of more than 40 per cent. ; in two other 

 cases the maximum was attained with a dilution of ten 

 parts in a billion, the increase being about 100 per cent. 



Table XII. — Effect of Extract of Thyroid Gland, of Iodine, and 



of Formaldehyde 



