ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 823 



causes of different importance acting together or separately. When 

 the stem is rudimentary or reduced to a bulb, and the leaves are 

 sessile, the nutritive equilibrium exercises only a feeble influence, 

 since the nutritive materials are all collected in one organ ; the 

 relative dimensions only of this organ are modified. The most 

 complex case is where the causes of etiolation combine, as when an 

 aquatic plant, furnished with a stem and petiolate leaves, is immersed 

 in the dark, as occurs in the first leaves of water-plants growing at a 

 great depth. 



Origin of Galls.* — In opposition to the view of Dr. Adler, 

 J. Paszlavszky has established that all rose-galls arise in leaf-buds 

 which have been punctured by Bhodites rosce. The female works in 

 three directions corresponding to the phyllotaxis of the rose, laying 

 her eggs, which are provided with a loug stalk, on the three leaves 

 which constitute a whorl. f All galls become in this way circular by 

 the shortening of the internodes. All terminal galls are originally 

 circular, and have become terminal by the gradual withering of the 

 leaves from the apex downwards. The ultimate form of the gall 

 depends greatly on the number of larvae that develope within it. 



B. CRYPTOGAMIA. 



Muscineae. 



Male Fructification of Polytrichum4 — K. Goebel investigates 

 the phenomena connected with the habitual prolification of the 

 antheridial receptacle or male fructification of Pohjtrichum. 



He finds that Leitgeb's rule, derived from the case of Fontinalis, 

 that the first antheridium springs from the apical cell, and is the 

 termination of the primary axis, is not of general application. In 

 Pohjtrichum, on the contrary, the large apical cell of the primary 

 axis may be recognized in the middle of the fructification ; the first 

 antheridium cannot therefore proceed from it. From each leaf- 

 forming segment beneath the leaf springs a group of antheridia. 

 It follows from this that the antheridia which form a group do not 

 stand at the same height, but are arranged in two or three superposed 

 rows. Among them stand a great number of densely packed para- 

 physes, which, together with the somewhat modified leaves, completely 

 enclose the antheridia. A leaf is produced of each segment of 

 the apical cell. The growing point of the stem is not, as in Fon- 

 tinalis and other genera, slender, but flattened, somewhat as in Lyco- 

 podium Selago. At a later period, when the antheridia are mature, 

 the growing point even lies in a cup-shaped depression. The 

 flattening of the growing point is caused by the growth of each 

 segment being stronger in its upper portion nearest the surface of 

 the stem than in its lower part. From the base of the young leaves 

 hairs spring at an early period on the side which faces the apical 

 cell ; antheridia have never been observed in this position. 



* Naturforscher, xv. (1SS2) p. 308. 



t The phyllotaxis of the rose is 2-5, five leaves making up two whorls. 



Ed. 



% Flora, lxv. (1S82) pp. 323-6 (1 pi.). 



