ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 825 



B. Physiology- * 



Cross-fertilization of Plants by Birds.f — Dr. Fritz Miiller de- 

 scribes the structure of the flowers of an American sbrub belonging to 

 tho genus Feijoa and order Myrtaceas, adapting them to cross-fertiliza- 

 tion by birds. When the flower is fully open, the petals roll up and 

 beconio soft and very sweet, exposing only their outer surface, which 

 is puro white ; but no honey is developed which would be attractive 

 to insects. The stamens are very numerous (50-60), dark blood-red, 

 expanding above into a crown more than an inch in diameter, and 

 with bright-yellow pollen. The blood-red stamens and pistil, yellow 

 pollen, snow-white petals, and dark sepals, make tho flowers, which 

 are quite exposed, very conspicuous ; and yet they appear to be 

 seldom visited by insects. But the petals are devoured by birds 

 belonging to the genus Thamnophilus, which, in so doing, necessarily 

 carry the pollen from one flower to another, either the neck or head 

 invariably coming into contact with the open anthers as they stoop 

 down to bite the petals. 



Evolution of Oxygen from Plants in the Microspectrum.f — In 

 pursuance of investigations already reportod,§ Herr N. Pringsheim 

 has carried on his researches on the portion of the solar spectrum 

 which has the greatest effect in promoting decomposition of carbonic 

 acid and consequent evolution of oxygen by plants. He uses for this 

 purpose the bacterian method of Engelmann, but his results are not 

 altogether in harmony with those of that observer. 



Pringsheim finds that there is no constant coincidence of tho 

 maxima of absorption and of exhalation of oxygen either in the red or 

 in the blue. Although the movement of bacteria in the red exhibits 

 generally great energy, yet its maximum possibly never lies at tho 

 spot of maximum absorption B \ C, but generally behind C, usually 

 nearly midway between C and D ; and its position is subject to not 

 inconsiderable variations even in different specimens of the same 

 plant. In the whole of the blue-violet end of the spectrum the 

 movement of bacteria is always extremely sluggish in comparison 

 with the strong absorption in the chlorophyll which always takes 

 place in this part. 



All brown and red algae have, in their absorption-spectrum, the 

 dark absorption-band in tho red corresponding to the chloroimyll- 

 band I ; but the maximum of evolution of oxygen is, in these plants, 

 never in the red, but far in the yellow and green. 



* This subdivision contains (1) Reproduction (including the formation of tho 

 Embryo and accompanying processes); (2) Germination ; (3) Nutrition ; (4) Growth; 

 (5) Respiration ; (6) Movement ; and (7) Chemical processes (including Fermen- 

 tation). 



f Kosmos, i. (188G) pp. 93-8. Sec Science, vii. (1886) pp. 441-2 (3 figs.). 



j Tringshcim's Jahrb. f. Wiss. Dot., xvii. (1886) pp. 162-206 (2 pis.); and 

 SB. K. Prcuss. Akad. Wiss. Berlin, vii. (1SS6) pp. 137-76 (2 pis.). 



§ Slc this Journal, ii. (1882) p. 220 ; ante, p. 105. 



