1886.] Eclipse of the Sun in 1886 observed at Grenada. 469 



lytic ferment which will convert fibrin into peptone and then into 

 leucin and tyrosin. 



2. This exists in the resting seed in the form a zymogen, which is 

 easily convertible into the ferment. 



3. The ferment acts best in a slightly acid medinm ; its activity is 

 hindered by neutral salts and destroyed by alkalis, and it is most 

 active at a temperature of 40° C. 



4. The process of germination is started or accompanied by a trans- 

 formation of the zymogen into ferment on the absorption of water and 

 the development of vegetable acids in the cells of the seed. 



5. The ferment so developed converts the proteids of the resting 

 seed into acid albumin or parapeptone, peptone, and crystalline 

 amides. 



6. The nitrogen travels from the cells of the seed to the growing 

 points in the form of the latter bodies and not in that of peptone or 

 other proteid. 



VII. " Preliminary Account of the Observations of the Eclipse 

 of the Sun at Grenada in August, 1886." By Captain 

 Darwix, R.E. Communicated by Lord Rayleigh, Sec. 

 U.S. Received November 25, 1886. 



The instruments allotted to me consisted of the coronagraph and 

 the prismatic camera ; the two instruments being mounted on the 

 same equatorial stand. 



The prismatic camera is the same instrument which was used at 

 the eclipses of 1882 and 1884. It consists of an ordinary photo- 

 graphic camera with a 60° prism placed in front of the lens. 



The coronagraph consists of a reflecting telescope arranged for 

 obtaining photographic records, and in which special precautions are 

 taken to avoid internally reflected light. 



This instrument was designed by Dr. Huggins, with the idea that 

 it might be possible to obtain photographs of the corona in sunlight, 

 that is at other times than at eclipses, and I was especially directed 

 to test the practicability of this method. The test could be applied 

 in two ways : — 



1st. By obtaining photographs shortly before or after the eclipse, 

 and comparing any irregularity that might appear in the halo round 

 the sun with any photographs of the corona taken during totality; a 

 similarity of form indicating that the corona had been photographed. 



2nd. To take photographs during partial eclipse. Then if the 

 light of the corona produces any eSect on the plate, the limb of the 

 moon should be visible against it. 



