162 MEMORANDA. 



aperture will receive the larger number of rays ; and If so, 

 then my statement is fully confirmed, tlat "large angles of 

 aperture are as useful for balsam-mounted objects as for 

 others." 



The distinction I hiive alluded to a!)ove, between the inten- 

 sity of illumination of the balsam-mounted object, and the 

 effect of large angles of aperture is alluded to by Dr, Robinson, 

 of Armagh, in his paper "On measuring the angular aperture 

 of object-glasses," published in the Proceedings of the Royal 

 Irish Academy, January 23, 1854, where he states in a note, 

 that the effect of mounting in balsam is, in fact, equivalent to 

 reducing the aperture of the objective below 100^, as far as 

 illumination is concerned^ thoujh a viuch larc/er one may be 

 required to take in the petwil. — J. W. Bailey, West Pointy 

 New Vo7'li. 



Mohl on Chlorophyll. — In a recent number of the ' Annals and 

 Magazine of Natural Histoi'y,' Mr. Henfrey has translated an 

 interesting paper by Mold on Chlorophyll. This paper thus 

 concludes : — 



"Gatherino; all these points together, — the occurrence of Cliloroi>liyll 

 in cells which contained no starch ; the occurrence of n;enihrane-like 

 Chlorophyll-structures, not preceded by any corresponding starch-struc- 

 ture, or accumulations of starch-grains ; the growth of Chlorophyll-glohules 

 after the starch-grains have vanished from tliem ; the simultaneous increase 

 in size of starch and Chlorophyll-globules in otlici' plants ; — we are neces- 

 sarily led to the conclusion, that Chlorojihyll is not ]iroduced by the 

 transformation of starch-grains, but that the two structures, though fre- 

 quently connected together, originate independently of each other. The 

 starch may exist earlier, and the Chlorophyll accumulate around the 

 starch-grains as around a nucleus — as may be seen so clearly in the 

 internal starch-bearing cells of a potato when exposed to the light, and, 

 in extremely numerous cases, in the leaves of buds ; and, on the contrarj^ 

 the starch-grains lying in Chlorophyll-globules may increase in size inde- 

 pendently, and even be formed in Chlorophyll which originally contained 

 no starch." 



Mr. Henfrey has added the following notes: — 



" My own observations fully confirm the statement that starch-grains 

 may originate in Chloroi)hyll- globules at first totallj' devoid of starch ; 1 

 have traced the formation of groups of starch-grains in this way in the 

 interior of Chlorophyll in the Hepaticee and other Cryptogamous plants. 

 There can be little doubt that the Chlorophyll belongs to the jirotoplasmic 

 substances of the cell-contents, and is capable of producing starch equally 

 with the colourless protoplasm. From the mode in which starch-grains 

 are formed, both in Chloropliyll and in colourless protoplasmic masses, I 

 am inclined to regard it as a product formed bj^ deposit or secretion on the 

 inside of cavities or vacuoles of the latter, by a process analogous to the 

 formation of the cellulose layers on the outside of the primordial utricle. 

 I do not find the protoplasmic nucleus described by Criiger in all starch- 

 grains. This would account for most of the phenomena observed. At 



