ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 525 



slightly tinged by reagents, that no means at present exists of 

 detecting them in situ. 



These facts are of the greatest importance in connection with 

 Strasburger's view of the unity of the entire plant. The author sug- 

 gests that the continuity of the protoplasm from cell to cell may be 

 an important factor in accounting for the contractility of the motile 

 organs. 



Pollination of Rulingia* — According to J. Urban, several species 

 of this Australian genus of Buttneriacese possess curious adaptations 

 to crossing by insect aid. The flowers are small (1 cm. or less in 

 diameter) and whitish. The pistil secretes nectar, which collects 

 about it or in the hollowed petals. At first tha stigma is closely 

 covered by five dilated staminodia, closely inflexed over it for a time, 

 but later separate. In B. pannosa there is well-marked proterandry, 

 the staminodia not separating, nor the stigma maturing, until the 

 stamens are all dehiscent. U. corylifolia, on the other hand, is 

 synacmic, the expansion of the sepals and the dehiscence of the 

 stamens occurring in regular succession, and being closely followed by 

 the successive removal of the staminodia from the mature stigma. 

 M. parviflora is intermediate between the two species already men- 

 tioned. Its flowers assume a rosy colour with age, like those of 

 Trillium grandiflorum, Weigelia, &c. 



Development of ChlorophyU-grains and Pigment-bodies, j — 

 Further investigation of these bodies by A. F. W. Schitnper leads 

 Mm to the conclusion that the growing point always contains differ- 

 entiated chlorophyll-bodies or their colourless matrix, and confirms 

 the view that these are not formed by rejuvenescence out of the cell- 

 protoplasm, but always by division from those previously existing, and 

 that they are the source of all the chlorophyll-bodies and starch- 

 generators of the tissue which developes from the apical meristem. 

 A very favourable instance of a green growing point is aff"orded by 

 the roots of Azolla, which contain bright green chlorophyll-grains in 

 their apical cells. They occur also in the growing points of the aerial 

 roots of epiphytal orchids, especially in Dendrobrium spectabile, and in 

 the roots of Lemna and the slenderer roots of Hydrocharis morsus- 

 rance. In the majority of cases, however, the growing point and the 

 merismatic parts of plants contain no chlorophyll, from the absence 

 of sufficient light ; and even when exposed to the light they frequently 

 contain only the colourless protoplasmic matrix of chlorophyll-g-rains, 

 i. e. starch-generators, as in the roots of seedlings of Zea Mays and 

 Phaseolus, and the aerial roots of Impatiens parviflora. 



Colourless growing points contain colourless starch-generators, 

 resulting from division, and not from rejuvenescence; these are 

 always found in the growing point of the stem of seedlings, and give 

 rise, by division, to all the chlorophyll-grains, starch-generators, and 

 pigment-bodies of the entire organism, except those of the roots, which 



* Ber. Deutsch. Bot. GeselL, i. (1883) pp. 53-6. 



t Bot. Ztg., xli. (1883) pp. 105-11, 121-31, 137-46, 153-62 (1 pi.). Cf. this 

 Journal, ante, p. 238. 



